Create particle effects directly inside Aseprite! Heos Particles is a script that lets you generate animated particles: sparks, explosions, smoke, rain, magic, and much more, without leaving your pixel art workflow.

Features

• 30+ ready‑to‑use presets (Sparks, Explosion, Smoke, Rain, Fireflies, Blood, Electricity, Petals, Vortex, Glitch, Magic, and many more)
• 30+ built‑in shapes: Square, Cross, Circle, Ring, Diamond, Arc, Arrow, Bolt, Bubble, Burst, Cloud, Comet, Crescent, Dash, Drop, Flame, Flower, Heart, Hexagon, Leaf, Line, Pentagon, Pixel, Snowflake, Sparkle, Spiral, Splat, Star, Triangle, X, and more
• Custom shape support: Use your own sprite as a particle by drawing on the "Heos_custom" layer
• Emit from a selection: Make a selection on the canvas, and particles will only spawn inside that area (randomly). If no selection exists, the whole sprite area is used
• Path‑based emission: Draw a trajectory on the "Heos_path" layer, and particles will follow it frame by frame (one pixel per frame defines the emitter's movement)
• Full control over size, speed, spin, gravity, color, and emission length — with optional evolution over lifetime
• Evolve system: Each property can either interpolate smoothly from start→end (Evolve ON) or pick random fixed values per particle (Evolve OFF)
• Emit over multiple frames (burst or continuous effect) with independent control over burst duration and particle lifetime
• Start frame control: Choose which frame the emission begins on
• Auto‑clears previous particles and manages frames intelligently
• Layer name customization: Create multiple particle systems by renaming the output layer
• Original colors mode: Custom shapes can keep their original pixel colors instead of being tinted

How to use

1. Place the script in your Aseprite scripts folder
2. Run it via File > Scripts > Heos Particles
3. Choose a preset or tweak the parameters in the Particle and Emission tabs
4. Optional: Click "Path layer" to create a trajectory layer, or "Custom layer" to draw your own particle shape
5. Click "Allons‑y!": The script creates a "Particles" layer and generates all frames

Understanding the parameters & the "Evolve" checkbox

Each particle property has a start and end value. The "Evolve" checkbox changes how these values are applied:

• Evolve ON → The property starts at the start value and linearly interpolates towards the end value over the particle's lifetime. For example, if Size evolve is ON, particles begin at size_start and gradually grow/shrink to size_end.
• Evolve OFF → Each particle picks a random constant value when it is born, and that value never changes during its life. For example, if Speed evolve is OFF, every particle moves at a random but fixed speed (some fast, some slow).

This allows two very different behaviors: smooth transitions vs. random variety.

Parameter reference

Parameter	What it does
Shape	Visual form of each particle (30+ built-in shapes, or Custom). "Pixel" is always 1px and ignores size sliders.
Color 1 & 2	Gradient colors. Evolve ON: particles fade from Color1 to Color2 over their lifetime. Evolve OFF: each particle picks a random fixed color between them.
Size	Particle size in pixels (1–16). size_start = initial size, size_end = final size. Evolve ON: grows/shrinks from start to end. Evolve OFF: each particle picks a random fixed size in that range.
Speed	Initial velocity in pixels per frame (1–150). Evolve ON: speed changes from speed_start to speed_end. Evolve OFF: each particle picks a random fixed speed.
Spin	Rotation speed in degrees per frame (–45 to 45). Positive = clockwise, negative = counter‑clockwise. Evolve ON: spin accelerates/decelerates from spin_start to spin_end. Evolve OFF: each particle gets a random constant spin rate.
Angle	Initial rotation angle of each particle in degrees (–180 to 180). Evolve ON: all particles start at angle_start and rotate to angle_end over their lifetime (synchronized sweep). Evolve OFF: each particle spawns at a random fixed angle between angle_start and angle_end.
Gravity	Acceleration in pixels per frame² affecting vertical motion. Negative = upward (floating), positive = downward. gravity_end sets final gravity value. Evolve ON: gravity changes smoothly from start to end. Evolve OFF: each particle picks a random fixed gravity.
Spread	Angle range (0–180°) in which particles are emitted. 0° = all in same direction, 180° = full hemisphere.
Direction	Central emission angle (–180 to 180°). Quick N/E/S/W buttons snap to cardinal directions.
Particles	Number of particles spawned each emission frame (1–300).
Lifetime	How many frames each particle lives (1–300).
Emit frames	How many consecutive frames the emitter keeps spawning new particles (1–300).
Start frame	First sprite frame where emission begins.
Keep original colors	(Custom shape only) When using a custom sprite, respect its original pixel colors instead of tinting with Color1/Color2.

Understanding "Emit frames" vs "Lifetime"

• Emit frames = duration of the burst (how long the source keeps shooting particles)
• Lifetime = how long each individual particle survives after being shot

If you set Emit frames = 1 and Lifetime = 30, you get a single explosion with particles that fade over 30 frames.
If you set Emit frames = 60 and Lifetime = 20, you get a continuous fountain: old particles die while new ones keep appearing.

Requirements

Aseprite 1.3 or newer.

Perfect for game effects, VFX, muzzle flashes, weather, ambient glows, and more.

Examples

Custom/Path

Simple presets:

Select on the canvas (to choose the source's location):

Tips

• To use a custom shape (as in the first example), click "Custom layer" to create the Heos_custom layer, draw your particle there, then set Shape to "Custom" in the script. The "Keep original colors" option lets you preserve your pixel art colors.
• To use Path, click "Path layer," create as many frames as you need, and paint a single pixel in any color. The pixels in the frames do not have to be consecutive — the script interpolates between keyframes.
• Multiple particle systems: Change the layer name in the script to create separate particle layers without overwriting each other.
• Selection-based emission: Make a selection on the canvas before generating to confine particles to that area.
• The "Evolve" system is key to achieving different effects: turn it ON for smooth transitions (like a fireball fading from yellow to red), OFF for random variety (like confetti with different sizes and speeds).
• If a particle isn't rendering its shape correctly, you'll probably need to increase its size. 

💬 Feedback & Support

I love seeing how you use Heos Particles in your projects. If you have questions, ideas, or just want to share what you've made, feel free to leave a comment or reach out directly. It's always great to see your work in action.

If you found this tool useful, taking a moment to leave a rating really helps. Thanks for the support. ❤️