diff --git a/examples/imgui_integration/Cargo.toml b/examples/imgui_integration/Cargo.toml
new file mode 100644
index 0000000..5fb22ae
--- /dev/null
+++ b/examples/imgui_integration/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "imgui_integration"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "=1.0.55"
+ggdt = { path = "../../ggdt" }
+ggdt_imgui = { path = "../../ggdt_imgui" }
+imgui = "0.11.0"
+serde = { version = "1.0.136", features = ["derive"] }
+serde_json = "1.0.79"
diff --git a/examples/imgui_integration/assets/arena.map.json b/examples/imgui_integration/assets/arena.map.json
new file mode 100644
index 0000000..d1e4a6f
--- /dev/null
+++ b/examples/imgui_integration/assets/arena.map.json
@@ -0,0 +1,9 @@
+{
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+  "height":30,
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+  ]
+}
\ No newline at end of file
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index 0000000..1801a11
Binary files /dev/null and b/examples/imgui_integration/assets/tiles.pcx differ
diff --git a/examples/imgui_integration/src/context.rs b/examples/imgui_integration/src/context.rs
new file mode 100644
index 0000000..3e209a4
--- /dev/null
+++ b/examples/imgui_integration/src/context.rs
@@ -0,0 +1,136 @@
+use crate::entities::{AnimationDef, EntityActivity, Event};
+use crate::support::{load_bitmap_atlas_autogrid, load_font, load_palette};
+use crate::tilemap::TileMap;
+use anyhow::Result;
+use ggdt::prelude::*;
+use std::collections::HashMap;
+use std::path::Path;
+use std::rc::Rc;
+
+pub struct CoreContext {
+	pub delta: f32,
+	pub camera_x: i32,
+	pub camera_y: i32,
+	pub transparent_color: u32,
+	pub system: System<Standard>,
+	pub palette: Palette,
+	pub font: BitmaskFont,
+	pub small_font: BitmaskFont,
+	pub entities: Entities,
+	pub event_publisher: EventPublisher<Event>,
+	pub tiles: Rc<BitmapAtlas<RgbaBitmap>>,
+	pub green_slime: Rc<BitmapAtlas<RgbaBitmap>>,
+	pub blue_slime: Rc<BitmapAtlas<RgbaBitmap>>,
+	pub orange_slime: Rc<BitmapAtlas<RgbaBitmap>>,
+	pub tilemap: TileMap,
+	pub slime_activity_states: Rc<HashMap<EntityActivity, Rc<AnimationDef>>>,
+	pub sprite_render_list: Vec<(EntityId, Vector2, RgbaBlitMethod)>,
+}
+
+impl CoreState<Standard> for CoreContext {
+	fn system(&self) -> &System<Standard> {
+		&self.system
+	}
+
+	fn system_mut(&mut self) -> &mut System<Standard> {
+		&mut self.system
+	}
+
+	fn delta(&self) -> f32 {
+		self.delta
+	}
+
+	fn set_delta(&mut self, delta: f32) {
+		self.delta = delta;
+	}
+}
+
+impl CoreStateWithEvents<Standard, Event> for CoreContext {
+	fn event_publisher(&mut self) -> &mut EventPublisher<Event> {
+		&mut self.event_publisher
+	}
+}
+
+pub struct SupportContext {
+	pub component_systems: ComponentSystems<CoreContext, CoreContext>,
+	pub event_listeners: EventListeners<Event, CoreContext>,
+	pub imgui: ggdt_imgui::ImGui,
+}
+
+impl SupportSystems for SupportContext {}
+
+impl SupportSystemsWithEvents<Standard, Event> for SupportContext {
+	type ContextType = CoreContext;
+
+	fn event_listeners(&mut self) -> &mut EventListeners<Event, Self::ContextType> {
+		&mut self.event_listeners
+	}
+}
+
+pub struct GameContext {
+	pub core: CoreContext,
+	pub support: SupportContext,
+}
+
+impl AppContext<Standard> for GameContext {
+	type CoreType = CoreContext;
+	type SupportType = SupportContext;
+
+	fn core(&mut self) -> &mut Self::CoreType {
+		&mut self.core
+	}
+
+	fn support(&mut self) -> &mut Self::SupportType {
+		&mut self.support
+	}
+}
+
+impl GameContext {
+	pub fn new(mut system: System<Standard>) -> Result<Self> {
+		let palette = load_palette(Path::new("./assets/db16.pal"))?;
+
+		let font = load_font(Path::new("./assets/dp.fnt"))?;
+		let small_font = load_font(Path::new("./assets/small.fnt"))?;
+
+		let tiles = Rc::new(load_bitmap_atlas_autogrid(Path::new("./assets/tiles.pcx"))?);
+		let green_slime = Rc::new(load_bitmap_atlas_autogrid(Path::new("./assets/green_slime.pcx"))?);
+		let blue_slime = Rc::new(load_bitmap_atlas_autogrid(Path::new("./assets/blue_slime.pcx"))?);
+		let orange_slime = Rc::new(load_bitmap_atlas_autogrid(Path::new("./assets/orange_slime.pcx"))?);
+
+		let mut tilemap = TileMap::load_from(Path::new("./assets/arena.map.json"))?;
+
+		let entities = Entities::new();
+		let component_systems = ComponentSystems::new();
+		let event_publisher = EventPublisher::new();
+		let event_listeners = EventListeners::new();
+		let imgui = ggdt_imgui::ImGui::new();
+
+		let slime_activity_states = HashMap::from([
+			(EntityActivity::Idle, Rc::new(AnimationDef::new(&[1, 2], true, 1.0, Some(3)))),
+			(EntityActivity::Walking, Rc::new(AnimationDef::new(&[1, 0, 2, 0], true, 0.25, Some(3)))),
+		]);
+
+		Ok(GameContext {
+			core: CoreContext {
+				delta: 0.0,
+				camera_x: 0,
+				camera_y: 0,
+				transparent_color: palette[0],
+				system,
+				palette,
+				font,
+				small_font,
+				entities,
+				event_publisher,
+				tiles,
+				green_slime,
+				blue_slime,
+				orange_slime,
+				tilemap,
+				slime_activity_states: Rc::new(slime_activity_states),
+				sprite_render_list: Vec::new(),
+			},
+			support: SupportContext { component_systems, event_listeners, imgui },
+		})
+	}
+}
diff --git a/examples/imgui_integration/src/entities.rs b/examples/imgui_integration/src/entities.rs
new file mode 100644
index 0000000..d9fc6b2
--- /dev/null
+++ b/examples/imgui_integration/src/entities.rs
@@ -0,0 +1,767 @@
+use crate::context::{CoreContext, GameContext};
+use crate::tilemap::TileMap;
+use ggdt::prelude::*;
+use std::collections::HashMap;
+use std::rc::Rc;
+
+pub const FRICTION: f32 = 0.5;
+pub const DEFAULT_PUSH_STRENGTH: f32 = 0.5;
+pub const DEFAULT_PUSH_DISSIPATION: f32 = 0.5;
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum EntityActivity {
+	Idle,
+	Walking,
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum Direction {
+	South = 0,
+	West = 1,
+	East = 2,
+	North = 3,
+}
+
+impl Direction {
+	pub fn new_random() -> Self {
+		use Direction::*;
+		match rnd_value(0, 3) {
+			0 => South,
+			1 => West,
+			2 => East,
+			3 => North,
+			_ => panic!("unknown random direction!"),
+		}
+	}
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum SlimeColor {
+	Green = 0,
+	Blue = 1,
+	Orange = 2,
+}
+
+impl SlimeColor {
+	pub fn new_random() -> Self {
+		use SlimeColor::*;
+		match rnd_value(0, 2) {
+			0 => Green,
+			1 => Blue,
+			2 => Orange,
+			_ => panic!("unknown random slime color!"),
+		}
+	}
+}
+
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub struct Force {
+	pub force: Vector2,
+	pub dissipation_factor: f32,
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+pub struct Activity(pub EntityActivity);
+
+pub struct AnimateByActivity(pub Rc<HashMap<EntityActivity, Rc<AnimationDef>>>);
+
+#[derive(Debug)]
+pub struct AnimationDef {
+	pub frames: &'static [usize],
+	pub loops: bool,
+	pub delay: f32,
+	pub multi_direction_offset: Option<usize>,
+}
+
+impl AnimationDef {
+	#[inline]
+	pub fn new(frames: &'static [usize], loops: bool, delay: f32, multi_direction_offset: Option<usize>) -> Self {
+		AnimationDef { frames, loops, delay, multi_direction_offset }
+	}
+}
+
+#[derive(Debug)]
+pub struct AnimationInstance {
+	pub def: Rc<AnimationDef>,
+	pub frame_index: usize,
+	pub frame_timer: f32,
+	pub complete: bool,
+	pub delay_override: Option<f32>,
+}
+
+impl AnimationInstance {
+	#[inline]
+	pub fn from(def: Rc<AnimationDef>) -> Self {
+		AnimationInstance {
+			def, //
+			frame_index: 0,
+			frame_timer: 0.0,
+			complete: false,
+			delay_override: None,
+		}
+	}
+
+	#[inline]
+	pub fn change_to(&mut self, def: Rc<AnimationDef>) {
+		self.def = def;
+		self.reset();
+	}
+
+	#[inline]
+	pub fn reset(&mut self) {
+		self.frame_index = 0;
+		self.frame_timer = 0.0;
+		self.complete = false;
+	}
+}
+
+pub struct Bounds {
+	pub width: u32,
+	pub height: u32,
+	pub radius: u32,
+}
+
+pub struct FacingDirection(pub Direction);
+
+pub struct Forces {
+	pub forces: Vec<Force>,
+}
+
+impl Forces {
+	pub fn new() -> Self {
+		Forces { forces: Vec::with_capacity(5) }
+	}
+
+	pub fn current_force(&self) -> Vector2 {
+		let mut total_force = Vector2::ZERO;
+		for force in self.forces.iter() {
+			total_force += force.force;
+		}
+		total_force
+	}
+
+	pub fn add(&mut self, force: Vector2, dissipation_factor: f32) {
+		self.forces.push(Force { force, dissipation_factor });
+	}
+
+	pub fn decay(&mut self) {
+		for force in self.forces.iter_mut() {
+			force.force *= force.dissipation_factor;
+		}
+		self.forces.retain(|f| !f.force.almost_zero(0.001));
+	}
+}
+
+pub struct IgnoresCollision;
+
+pub struct IgnoresFriction;
+
+pub struct MovementSpeed(pub f32);
+
+pub struct Position(pub Vector2);
+
+pub struct Pushable;
+
+pub struct Pusher {
+	pub strength: f32,
+	pub push_force_dissipation: f32,
+}
+
+impl Pusher {
+	pub fn new() -> Self {
+		Pusher {
+			strength: DEFAULT_PUSH_STRENGTH, //
+			push_force_dissipation: DEFAULT_PUSH_DISSIPATION,
+		}
+	}
+}
+
+pub struct RandomlyWalksAround {
+	pub min_walk_time: f32,
+	pub max_walk_time: f32,
+	pub chance_to_move: u32,
+	pub min_cooldown: f32,
+	pub max_cooldown: f32,
+	pub cooldown_timer: f32,
+}
+
+impl RandomlyWalksAround {
+	pub fn new(
+		min_walk_time: f32,
+		max_walk_time: f32,
+		chance_to_move: u32,
+		min_cooldown: f32,
+		max_cooldown: f32,
+	) -> Self {
+		RandomlyWalksAround {
+			min_walk_time,
+			max_walk_time,
+			chance_to_move,
+			min_cooldown,
+			max_cooldown,
+			cooldown_timer: 0.0,
+		}
+	}
+
+	pub fn should_start_walking(&self) -> bool {
+		rnd_value(0, 100) < self.chance_to_move
+	}
+}
+
+pub struct Slime;
+
+pub struct Sprite {
+	pub atlas: Rc<BitmapAtlas<RgbaBitmap>>,
+	pub index: usize,
+}
+
+pub struct SpriteIndexByDirection {
+	pub base_index: usize,
+}
+
+pub struct Velocity(pub Vector2);
+
+pub struct WalkingTime(pub f32);
+
+pub fn init_entities(entities: &mut Entities) {
+	entities.init_components::<Activity>();
+	entities.init_components::<AnimateByActivity>();
+	entities.init_components::<AnimationDef>();
+	entities.init_components::<AnimationInstance>();
+	entities.init_components::<Bounds>();
+	entities.init_components::<FacingDirection>();
+	entities.init_components::<Forces>();
+	entities.init_components::<IgnoresCollision>();
+	entities.init_components::<IgnoresFriction>();
+	entities.init_components::<MovementSpeed>();
+	entities.init_components::<Position>();
+	entities.init_components::<Pushable>();
+	entities.init_components::<Pusher>();
+	entities.init_components::<RandomlyWalksAround>();
+	entities.init_components::<Slime>();
+	entities.init_components::<Sprite>();
+	entities.init_components::<SpriteIndexByDirection>();
+	entities.init_components::<Velocity>();
+	entities.init_components::<WalkingTime>();
+	entities.remove_all_entities();
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+pub enum Event {
+	AnimationFinished(EntityId),
+	MoveForward(EntityId),
+	Remove(EntityId),
+	SetActivity(EntityId, EntityActivity),
+	TurnAndMove(EntityId, Direction),
+}
+
+fn event_handler(event: &Event, context: &mut CoreContext) -> bool {
+	match event {
+		Event::AnimationFinished(entity) => {
+			// no-op
+		}
+		Event::MoveForward(entity) => {
+			if context.entities.has_entity(*entity) {
+				move_entity_forward(context, *entity);
+			}
+		}
+		Event::Remove(entity) => {
+			if context.entities.has_entity(*entity) {
+				remove_entity(&mut context.entities, *entity);
+			}
+		}
+		Event::SetActivity(entity, activity) => {
+			if context.entities.has_entity(*entity) {
+				set_entity_activity(&mut context.entities, *entity, *activity);
+			}
+		}
+		Event::TurnAndMove(entity, direction) => {
+			if context.entities.has_entity(*entity) {
+				turn_and_move_entity(context, *entity, *direction);
+			}
+		}
+	};
+	false
+}
+
+pub fn init_events(event_listener: &mut EventListeners<Event, CoreContext>) {
+	event_listener.clear();
+	event_listener.add(event_handler);
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+pub fn move_entity_forward(context: &mut CoreContext, entity: EntityId) {
+	let mut velocities = context.entities.components_mut::<Velocity>();
+	let facing_directions = context.entities.components::<FacingDirection>();
+	let movement_speeds = context.entities.components::<MovementSpeed>();
+
+	let velocity = velocities.get_mut(&entity).unwrap();
+	let facing_direction = facing_directions.get(&entity).unwrap();
+	let movement_speed = movement_speeds.get(&entity).unwrap();
+
+	let movement = match facing_direction.0 {
+		Direction::North => Vector2::UP * movement_speed.0,
+		Direction::East => Vector2::RIGHT * movement_speed.0,
+		Direction::West => Vector2::LEFT * movement_speed.0,
+		Direction::South => Vector2::DOWN * movement_speed.0,
+	};
+
+	velocity.0 += movement;
+}
+
+fn move_entity_with_collision(
+	position: &mut Position,
+	bounds: &Bounds,
+	velocity: Option<&Velocity>,
+	forces: Option<&Forces>,
+	map: &TileMap,
+	delta: f32,
+) -> bool {
+	const NUM_STEPS: usize = 2;
+	const STEP_SCALE: f32 = 1.0 / NUM_STEPS as f32;
+
+	let mut collided = false;
+
+	// apply entity velocity + force (if any/either) and exit early with no collision if this entity
+	// has no movement ... no need to check collisions in such a case
+	let mut step_velocity = Vector2::ZERO;
+	if let Some(velocity) = velocity {
+		step_velocity += velocity.0 * delta;
+	}
+	if let Some(forces) = forces {
+		step_velocity += forces.current_force();
+	}
+	if step_velocity.nearly_equal(Vector2::ZERO, 0.00001) {
+		return collided;
+	}
+
+	// entity is actually moving, so check collisions and move accordingly
+	step_velocity *= STEP_SCALE;
+	for _ in 0..NUM_STEPS {
+		let old_position = position.0;
+
+		position.0.x += step_velocity.x;
+		if map.is_colliding(&Rect::new(position.0.x as i32, position.0.y as i32, bounds.width, bounds.height)) {
+			collided = true;
+			position.0.x = old_position.x;
+		}
+
+		position.0.y += step_velocity.y;
+		if map.is_colliding(&Rect::new(position.0.x as i32, position.0.y as i32, bounds.width, bounds.height)) {
+			collided = true;
+			position.0.y = old_position.y;
+		}
+	}
+
+	collided
+}
+
+pub fn remove_entity(entities: &mut Entities, entity: EntityId) {
+	entities.remove_entity(entity);
+}
+
+pub fn set_entity_activity(entities: &mut Entities, entity: EntityId, new_activity: EntityActivity) {
+	let mut activities = entities.components_mut::<Activity>();
+	let mut activity = activities.get_mut(&entity).unwrap();
+
+	// only change the activity, and more importantly, the animation if we are actually applying
+	// an actual activity change from what it was before
+	if activity.0 != new_activity {
+		activity.0 = new_activity;
+
+		let animate_by_activitys = entities.components::<AnimateByActivity>();
+		if let Some(animate_by_activity) = animate_by_activitys.get(&entity) {
+			if let Some(new_animation_def) = animate_by_activity.0.get(&new_activity) {
+				let mut animations = entities.components_mut::<AnimationInstance>();
+				let animation = animations.get_mut(&entity).unwrap();
+				animation.change_to(new_animation_def.clone());
+			}
+		}
+	}
+}
+
+pub fn turn_and_move_entity(context: &mut CoreContext, entity: EntityId, direction: Direction) {
+	// can this entity currently move at all?
+	let activities = context.entities.components::<Activity>();
+	if let Some(activity) = activities.get(&entity) {
+		if activity.0 != EntityActivity::Idle && activity.0 != EntityActivity::Walking {
+			return;
+		}
+	}
+	drop(activities);
+
+	// make the entity face in the direction specified
+	let mut facing_directions = context.entities.components_mut::<FacingDirection>();
+	let facing_direction = facing_directions.get_mut(&entity).unwrap();
+	facing_direction.0 = direction;
+	drop(facing_directions);
+
+	move_entity_forward(context, entity);
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+fn update_system_movement(context: &mut CoreContext) {
+	let mut positions = context.entities.components_mut::<Position>().unwrap();
+	let velocities = context.entities.components::<Velocity>();
+	let forces = context.entities.components::<Forces>();
+	let bounds = context.entities.components::<Bounds>();
+	let ignores_collision = context.entities.components::<IgnoresCollision>();
+
+	for (entity, position) in positions.iter_mut() {
+		if ignores_collision.contains_key(entity) {
+			if let Some(velocity) = velocities.get(entity) {
+				position.0 += velocity.0 * context.delta;
+			}
+		} else {
+			let velocity = velocities.get(entity);
+			let force = forces.get(entity);
+
+			if velocity.is_some() || force.is_some() {
+				move_entity_with_collision(
+					position,
+					bounds.get(entity).unwrap(),
+					velocity,
+					force,
+					&context.tilemap,
+					context.delta,
+				);
+			}
+		}
+	}
+}
+
+fn update_system_friction(context: &mut CoreContext) {
+	let mut velocities = context.entities.components_mut::<Velocity>().unwrap();
+	let ignores_friction = context.entities.components::<IgnoresFriction>();
+
+	for (entity, velocity) in velocities.iter_mut() {
+		if !ignores_friction.contains_key(entity) {
+			velocity.0 *= FRICTION;
+			if velocity.0.almost_zero(0.001) {
+				velocity.0 = Vector2::ZERO;
+			}
+		}
+	}
+}
+
+fn update_system_force_decay(context: &mut CoreContext) {
+	let mut forces = context.entities.components_mut::<Forces>().unwrap();
+	for (_, force) in forces.iter_mut() {
+		force.decay();
+	}
+}
+
+fn update_system_pushing(context: &mut CoreContext) {
+	let positions = context.entities.components::<Position>();
+	let bounds = context.entities.components::<Bounds>();
+	let mut forces = context.entities.components_mut::<Forces>();
+	let pushers = context.entities.components::<Pusher>().unwrap();
+	let pushable = context.entities.components::<Pushable>().unwrap();
+
+	// TODO: this is slow
+
+	for (pusher_entity, pusher) in pushers.iter() {
+		let pusher_position = positions.get(pusher_entity).unwrap();
+		let pusher_bounds = bounds.get(pusher_entity).unwrap();
+		let pusher_circle = Circle::new(pusher_position.0.x as i32, pusher_position.0.y as i32, pusher_bounds.radius);
+
+		for (pushable_entity, pushable) in pushable.iter() {
+			// don't push ourself ...
+			if *pushable_entity == *pusher_entity {
+				continue;
+			}
+
+			let pushable_position = positions.get(pushable_entity).unwrap();
+			let pushable_bounds = bounds.get(pushable_entity).unwrap();
+			let pushable_circle = Circle::new(
+				pushable_position.0.x as i32, //
+				pushable_position.0.y as i32,
+				pushable_bounds.radius,
+			);
+
+			if pusher_circle.overlaps(&pushable_circle) {
+				let mut push_direction = (pushable_position.0 - pusher_position.0).normalize();
+				// this can happen if the pusher's and pushable's positions are exactly the same. we just need to
+				// "break the tie" so to speak ...
+				if !push_direction.x.is_normal() || !push_direction.y.is_normal() {
+					push_direction = Vector2::UP; // TODO: use one of their facing directions? which one?
+				}
+
+				let pushable_force = forces.get_mut(pushable_entity).unwrap();
+				pushable_force.add(push_direction * pusher.strength, pusher.push_force_dissipation);
+			}
+		}
+	}
+}
+
+fn update_system_animation(context: &mut CoreContext) {
+	let mut animations = context.entities.components_mut::<AnimationInstance>().unwrap();
+
+	for (entity, animation) in animations.iter_mut() {
+		if animation.complete {
+			continue;
+		}
+
+		animation.frame_timer += context.delta;
+
+		let delay = if let Some(delay_override) = animation.delay_override {
+			delay_override //
+		} else {
+			animation.def.delay
+		};
+
+		if animation.frame_timer >= delay {
+			// move to the next frame in the current sequence
+			animation.frame_timer = 0.0;
+			if animation.frame_index == (animation.def.frames.len() - 1) {
+				// we're at the last frame in the current sequence
+				if !animation.def.loops {
+					animation.complete = true;
+					context.event_publisher.queue(Event::AnimationFinished(*entity));
+				} else {
+					animation.frame_index = 0;
+				}
+			} else {
+				animation.frame_index += 1;
+			}
+		}
+	}
+}
+
+fn update_system_set_sprite_index_from_animation(context: &mut CoreContext) {
+	let animations = context.entities.components::<AnimationInstance>().unwrap();
+	let mut sprites = context.entities.components_mut::<Sprite>();
+	let facing_directions = context.entities.components::<FacingDirection>();
+
+	for (entity, animation) in animations.iter() {
+		if let Some(sprite) = sprites.get_mut(entity) {
+			// base animation sprite-sheet index for the current animation state
+			let mut index = animation.def.frames[animation.frame_index];
+
+			// add multi-direction offset if applicable
+			let multi_direction_offset = animation.def.multi_direction_offset;
+			let facing_direction = facing_directions.get(entity);
+			if multi_direction_offset.is_some() && facing_direction.is_some() {
+				index += multi_direction_offset.unwrap() * facing_direction.unwrap().0 as usize;
+			}
+
+			sprite.index = index;
+		}
+	}
+}
+
+fn update_system_set_sprite_index_by_direction(context: &mut CoreContext) {
+	let sprite_index_by_directions = context.entities.components::<SpriteIndexByDirection>().unwrap();
+	let mut sprites = context.entities.components_mut::<Sprite>();
+	let facing_directions = context.entities.components::<FacingDirection>();
+
+	for (entity, sprite_index_by_direction) in sprite_index_by_directions.iter() {
+		if let Some(sprite) = sprites.get_mut(entity) {
+			if let Some(facing_direction) = facing_directions.get(entity) {
+				sprite.index = sprite_index_by_direction.base_index + facing_direction.0 as usize;
+			}
+		}
+	}
+}
+
+fn update_system_walking_time(context: &mut CoreContext) {
+	let mut walking_times = context.entities.components_mut::<WalkingTime>().unwrap();
+
+	for (entity, walking_time) in walking_times.iter_mut() {
+		if walking_time.0 > 0.0 {
+			walking_time.0 -= context.delta;
+			context.event_publisher.queue(Event::MoveForward(*entity));
+		}
+	}
+
+	// remove walking time components whose timers have elapsed
+	walking_times.retain(|_, comp| comp.0 > 0.0);
+}
+
+fn update_system_randomly_walk_around(context: &mut CoreContext) {
+	let mut randomly_walk_arounds = context.entities.components_mut::<RandomlyWalksAround>().unwrap();
+	let activities = context.entities.components::<Activity>();
+	let mut walking_times = context.entities.components_mut::<WalkingTime>().unwrap();
+
+	for (entity, randomly_walk_around) in randomly_walk_arounds.iter_mut() {
+		if let Some(activity) = activities.get(entity) {
+			if activity.0 == EntityActivity::Idle {
+				if randomly_walk_around.cooldown_timer > 0.0 {
+					randomly_walk_around.cooldown_timer -= context.delta;
+					if randomly_walk_around.cooldown_timer < 0.0 {
+						randomly_walk_around.cooldown_timer = 0.0;
+					}
+				} else if randomly_walk_around.should_start_walking() {
+					randomly_walk_around.cooldown_timer = rnd_value(
+						randomly_walk_around.min_cooldown, //
+						randomly_walk_around.max_cooldown,
+					);
+
+					let direction = Direction::new_random();
+					let walk_time = rnd_value(randomly_walk_around.min_walk_time, randomly_walk_around.max_walk_time);
+
+					walking_times.insert(*entity, WalkingTime(walk_time));
+					context.event_publisher.queue(Event::TurnAndMove(*entity, direction));
+				}
+			}
+		}
+	}
+}
+
+fn update_system_current_entity_activity(context: &mut CoreContext) {
+	let activities = context.entities.components::<Activity>().unwrap();
+	let velocities = context.entities.components::<Velocity>();
+
+	for (entity, activity) in activities.iter() {
+		// try to detect current entity activity based on it's own movement speed
+		// (intentionally NOT checking force velocity!)
+		if let Some(velocity) = velocities.get(entity) {
+			match activity.0 {
+				EntityActivity::Idle => {
+					if velocity.0.length_squared() > 0.0 {
+						context.event_publisher.queue(Event::SetActivity(*entity, EntityActivity::Walking));
+					}
+				}
+				EntityActivity::Walking => {
+					if velocity.0.almost_zero(0.001) {
+						context.event_publisher.queue(Event::SetActivity(*entity, EntityActivity::Idle));
+					}
+				}
+				_ => {}
+			}
+		}
+	}
+}
+
+fn render_system_sprites(context: &mut CoreContext) {
+	context.sprite_render_list.clear();
+
+	let sprites = context.entities.components::<Sprite>().unwrap();
+	let positions = context.entities.components::<Position>().unwrap();
+
+	// build up list of entities to be rendered with their positions so we can sort them
+	// and render these entities with a proper y-based sort order
+	for (entity, _) in sprites.iter() {
+		let mut blit_method = RgbaBlitMethod::Transparent(context.transparent_color);
+
+		let position = positions.get(entity).unwrap();
+		context.sprite_render_list.push((*entity, position.0, blit_method));
+	}
+	context.sprite_render_list.sort_unstable_by(|a, b| (a.1.y as i32).cmp(&(b.1.y as i32)));
+
+	// now render them in the correct order ...
+	for (entity, position, blit_method) in context.sprite_render_list.iter() {
+		let sprite = sprites.get(entity).unwrap();
+		context.system.res.video.blit_atlas(
+			blit_method.clone(),
+			&sprite.atlas,
+			sprite.index,
+			position.x as i32 - context.camera_x,
+			position.y as i32 - context.camera_y,
+		);
+	}
+}
+
+fn render_system_entity_ids(context: &mut CoreContext) {
+	let sprites = context.entities.components::<Sprite>().unwrap();
+	let positions = context.entities.components::<Position>().unwrap();
+
+	for (entity, _) in sprites.iter() {
+		let position = positions.get(entity).unwrap();
+
+		let x = position.0.x as i32 - context.camera_x;
+		let y = position.0.y as i32 - context.small_font.line_height() as i32 - context.camera_y;
+		context.system.res.video.print_string(
+			&entity.to_string(),
+			x,
+			y,
+			FontRenderOpts::Color(context.palette[15]),
+			&context.small_font,
+		);
+	}
+}
+
+pub fn init_component_system(cs: &mut ComponentSystems<CoreContext, CoreContext>) {
+	cs.reset();
+	cs.add_update_system(update_system_current_entity_activity);
+	cs.add_update_system(update_system_walking_time);
+	cs.add_update_system(update_system_pushing);
+	cs.add_update_system(update_system_movement);
+	cs.add_update_system(update_system_friction);
+	cs.add_update_system(update_system_force_decay);
+	cs.add_update_system(update_system_randomly_walk_around);
+	cs.add_update_system(update_system_animation);
+	cs.add_update_system(update_system_set_sprite_index_from_animation);
+	cs.add_update_system(update_system_set_sprite_index_by_direction);
+	cs.add_render_system(render_system_sprites);
+	cs.add_render_system(render_system_entity_ids);
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+pub fn init(context: &mut GameContext) {
+	init_entities(&mut context.core.entities);
+	init_component_system(&mut context.support.component_systems);
+	init_events(&mut context.support.event_listeners);
+	context.core.event_publisher.clear();
+}
+
+pub fn new_slime_entity(
+	context: &mut CoreContext,
+	x: i32,
+	y: i32,
+	direction: Direction,
+	color: SlimeColor,
+) -> EntityId {
+	let id = context.entities.new_entity();
+
+	let (
+		atlas, //
+		chance_to_move,
+		movement_speed,
+		min_walk_time,
+		max_walk_time,
+		min_walk_cooldown,
+		max_walk_cooldown,
+	) = match color {
+		SlimeColor::Green => (context.green_slime.clone(), 10, 8.0, 0.5, 2.0, 0.5, 5.0),
+		SlimeColor::Blue => (context.blue_slime.clone(), 40, 12.0, 0.5, 2.0, 0.5, 3.0),
+		SlimeColor::Orange => (context.orange_slime.clone(), 90, 24.0, 0.5, 1.0, 0.5, 2.0),
+	};
+
+	let activity = EntityActivity::Idle;
+	let animate_by_activity = AnimateByActivity(context.slime_activity_states.clone());
+	let animation = AnimationInstance::from(animate_by_activity.0.get(&activity).unwrap().clone());
+
+	context.entities.add_component(id, Slime);
+	context.entities.add_component(id, Position(Vector2::new(x as f32, y as f32)));
+	context.entities.add_component(id, Velocity(Vector2::ZERO));
+	context.entities.add_component(id, Forces::new());
+	context.entities.add_component(id, Bounds { width: 16, height: 16, radius: 8 });
+	context.entities.add_component(id, FacingDirection(direction));
+	context.entities.add_component(id, Sprite { atlas, index: 0 });
+	context.entities.add_component(id, Activity(activity));
+	context.entities.add_component(id, animate_by_activity);
+	context.entities.add_component(id, animation);
+	context.entities.add_component(
+		id,
+		RandomlyWalksAround::new(
+			min_walk_time, //
+			max_walk_time,
+			chance_to_move,
+			min_walk_cooldown,
+			max_walk_cooldown,
+		),
+	);
+	context.entities.add_component(id, MovementSpeed(movement_speed));
+	context.entities.add_component(id, Pusher::new());
+	context.entities.add_component(id, Pushable);
+
+	id
+}
diff --git a/examples/imgui_integration/src/main.rs b/examples/imgui_integration/src/main.rs
new file mode 100644
index 0000000..0547ad0
--- /dev/null
+++ b/examples/imgui_integration/src/main.rs
@@ -0,0 +1,108 @@
+mod context;
+mod entities;
+mod support;
+mod tilemap;
+
+use anyhow::{Context, Result};
+
+use crate::context::GameContext;
+use crate::tilemap::{TILE_HEIGHT, TILE_WIDTH};
+use ggdt::prelude::*;
+
+pub struct DemoState;
+
+impl AppState<GameContext> for DemoState {
+	fn update(&mut self, state: State, context: &mut GameContext) -> Option<StateChange<GameContext>> {
+		if context.core.system.res.keyboard.is_key_pressed(Scancode::Escape) {
+			return Some(StateChange::Pop(1));
+		}
+
+		let ui = context.support.imgui.new_frame(&context.core.system.res.video);
+		ui.window("Entities").build(|| {
+			ui.text("TODO: display entity list or something");
+		});
+
+		let ui_focused = ui.is_window_hovered_with_flags(imgui::WindowHoveredFlags::ANY_WINDOW)
+			|| ui.is_window_focused_with_flags(imgui::WindowFocusedFlags::ANY_WINDOW);
+
+		if !ui_focused {
+			if context.core.system.res.mouse.is_button_down(1) {
+				context.core.camera_x -= context.core.system.res.mouse.x_delta() * 2;
+				context.core.camera_y -= context.core.system.res.mouse.y_delta() * 2;
+			}
+		}
+
+		context.support.do_events(&mut context.core);
+		context.support.component_systems.update(&mut context.core);
+
+		None
+	}
+
+	fn render(&mut self, state: State, context: &mut GameContext) {
+		context.core.system.res.video.clear(context.core.palette[0]);
+		context.core.tilemap.draw(
+			&mut context.core.system.res.video,
+			&context.core.tiles,
+			context.core.camera_x,
+			context.core.camera_y,
+			context.core.transparent_color,
+		);
+		context.support.component_systems.render(&mut context.core);
+
+		context.support.imgui.render(&mut context.core.system.res.video);
+	}
+
+	fn transition(&mut self, state: State, context: &mut GameContext) -> bool {
+		true
+	}
+
+	fn state_change(&mut self, new_state: State, old_state: State, context: &mut GameContext) {
+		if new_state == State::Pending {
+			entities::init(context);
+			for _ in 0..10 {
+				let (x, y) = context.core.tilemap.get_random_spawnable_coordinates();
+				entities::new_slime_entity(
+					&mut context.core,
+					x * TILE_WIDTH as i32,
+					y * TILE_HEIGHT as i32,
+					entities::Direction::new_random(),
+					entities::SlimeColor::new_random(),
+				);
+			}
+		}
+	}
+}
+
+fn main() -> Result<()> {
+	let config = StandardConfig::variable_screen_size(640, 480).scale_factor(2);
+	let mut system = SystemBuilder::new() //
+		.window_title("ImGui Example Integration")
+		.vsync(true)
+		.build(config)?;
+	system.res.cursor.enable_cursor(true);
+	let mut game = GameContext::new(system)?;
+
+	let mut states = States::new();
+	states.push(DemoState);
+
+	let mut last_ticks = game.core.system.ticks();
+
+	'mainloop: while !states.is_empty() {
+		game.core.system.res.update_event_state()?;
+		for event in game.core.system.event_pump.poll_iter() {
+			game.core.system.res.handle_event(&event)?;
+			game.support.imgui.handle_event(&event);
+			if event == SystemEvent::Quit {
+				break 'mainloop;
+			}
+		}
+
+		last_ticks = game.core.update_frame_delta(last_ticks);
+		states.update(&mut game);
+		game.core.system.update()?;
+		states.render(&mut game);
+		game.core.system.display()?;
+	}
+
+	Ok(())
+}
diff --git a/examples/imgui_integration/src/support.rs b/examples/imgui_integration/src/support.rs
new file mode 100644
index 0000000..5eb0648
--- /dev/null
+++ b/examples/imgui_integration/src/support.rs
@@ -0,0 +1,18 @@
+use crate::tilemap::{TILE_HEIGHT, TILE_WIDTH};
+use anyhow::{Context, Result};
+use ggdt::prelude::*;
+
+pub fn load_palette(path: &std::path::Path) -> Result<Palette> {
+	Palette::load_from_file(path, PaletteFormat::Vga).context(format!("Loading palette: {:?}", path))
+}
+
+pub fn load_font(path: &std::path::Path) -> Result<BitmaskFont> {
+	BitmaskFont::load_from_file(path).context(format!("Loading font: {:?}", path))
+}
+
+pub fn load_bitmap_atlas_autogrid(path: &std::path::Path) -> Result<BitmapAtlas<RgbaBitmap>> {
+	let (bmp, _) = RgbaBitmap::load_file(path).context(format!("Loading bitmap atlas: {:?}", path))?;
+	let mut atlas = BitmapAtlas::new(bmp);
+	atlas.add_grid(TILE_WIDTH, TILE_HEIGHT)?;
+	Ok(atlas)
+}
diff --git a/examples/imgui_integration/src/tilemap.rs b/examples/imgui_integration/src/tilemap.rs
new file mode 100644
index 0000000..0f69245
--- /dev/null
+++ b/examples/imgui_integration/src/tilemap.rs
@@ -0,0 +1,110 @@
+use anyhow::{Context, Result};
+use ggdt::prelude::*;
+
+pub const TILE_WIDTH: u32 = 16;
+pub const TILE_HEIGHT: u32 = 16;
+
+pub const TILE_FLAG_NONE: i32 = 1;
+pub const TILE_FLAG_COLLISION: i32 = 0;
+pub const TILE_FLAG_SPAWNABLE: i32 = 1;
+
+#[derive(Debug, serde::Deserialize)]
+pub struct TileMap {
+	width: u32,
+	height: u32,
+	layers: Vec<Box<[i32]>>,
+}
+
+impl TileMap {
+	pub fn load_from(path: &std::path::Path) -> Result<Self> {
+		let f = std::fs::File::open(path)?;
+		let reader = std::io::BufReader::new(f);
+		serde_json::from_reader(reader).context(format!("Loading json tilemap: {:?}", path))
+	}
+
+	#[inline]
+	pub fn index_to(&self, x: i32, y: i32) -> Option<usize> {
+		if x >= 0 && y >= 0 && x < self.width as i32 && y < self.height as i32 {
+			Some(((y * self.width as i32) + x) as usize)
+		} else {
+			None
+		}
+	}
+
+	#[inline]
+	pub fn collision(&self) -> &[i32] {
+		&self.layers[2]
+	}
+
+	pub fn is_colliding(&self, rect: &Rect) -> bool {
+		let x1 = rect.x / TILE_WIDTH as i32;
+		let y1 = rect.y / TILE_HEIGHT as i32;
+		let x2 = rect.right() / TILE_WIDTH as i32;
+		let y2 = rect.bottom() / TILE_HEIGHT as i32;
+
+		for y in y1..=y2 {
+			for x in x1..=x2 {
+				match self.index_to(x, y) {
+					Some(index) => {
+						if self.collision()[index] == TILE_FLAG_COLLISION {
+							return true;
+						}
+					}
+					None => return true,
+				}
+			}
+		}
+		false
+	}
+
+	pub fn draw(
+		&self,
+		dest: &mut RgbaBitmap,
+		tiles: &BitmapAtlas<RgbaBitmap>,
+		camera_x: i32,
+		camera_y: i32,
+		transparent_color: u32,
+	) {
+		let xt = camera_x / TILE_WIDTH as i32;
+		let yt = camera_y / TILE_HEIGHT as i32;
+		let xp = camera_x % TILE_WIDTH as i32;
+		let yp = camera_y % TILE_HEIGHT as i32;
+
+		let tiles_y = (dest.height() as f32 / TILE_HEIGHT as f32).ceil() as i32 + 1;
+		let tiles_x = (dest.width() as f32 / TILE_WIDTH as f32).ceil() as i32 + 1;
+
+		for y in 0..tiles_y {
+			for x in 0..tiles_x {
+				if let Some(index) = self.index_to(x + xt, y + yt) {
+					let xd = (x * TILE_WIDTH as i32) - xp;
+					let yd = (y * TILE_HEIGHT as i32) - yp;
+
+					let lower = self.layers[0][index];
+					if lower >= 0 {
+						dest.blit_region(RgbaBlitMethod::Solid, tiles.bitmap(), &tiles[lower as usize], xd, yd);
+					}
+					let upper = self.layers[1][index];
+					if upper >= 0 {
+						dest.blit_region(
+							RgbaBlitMethod::Transparent(transparent_color),
+							tiles.bitmap(),
+							&tiles[upper as usize],
+							xd,
+							yd,
+						);
+					}
+				}
+			}
+		}
+	}
+
+	pub fn get_random_spawnable_coordinates(&self) -> (i32, i32) {
+		loop {
+			let x = rnd_value(0, self.width as i32 - 1);
+			let y = rnd_value(0, self.height as i32 - 1);
+			if self.collision()[self.index_to(x, y).unwrap()] == TILE_FLAG_SPAWNABLE {
+				return (x, y);
+			}
+		}
+	}
+}