Powder Lab

A falling-sand physics sandbox built for CrazyGames. Pure HTML5 + vanilla JS: no build step, no dependencies, and no audio or image files (every sound is synthesized).

Open index.html through any static server (for example python3 -m http.server) to play.

What's in it

• 142 elements in 8 categories: powders, liquids, gases, solids, life, energy, explosives and special. Highlights: portals, white hole, vortex, stasis field, mini sun, volcano, meteor, cluster and cryo bombs, phoenix, ghost, saplings that grow full trees, lead-to-gold alchemy, uranium meltdowns, stardust that falls up.
• Atoms (currency) come from missions, level-ups, discoveries, a 7-day daily streak, big combos, every 2,500 pixels destroyed and an optional rewarded ad. Spend them in the Shop on premium elements and extra save slots.
• Save slots: 3 to start (up to 12), each with a thumbnail and an editable name. Save and Load buttons in the right panel ask which slot to use.
• Real systems, not just colors. Heat spreads between cells, and materials melt, boil, freeze and condense. Burning spreads through the heat model, electricity travels along metal and water, explosions throw debris around as physics particles, and lightning, lasers, fireworks, black holes, cloners, viruses and fish each have their own behaviour.
• Emergent chains. Burning wood can leave coal, burning coal can melt stone into lava, lava meeting water turns into obsidian, and glass shattered by an explosion becomes glitter.
• Progression loop. Creating an element in the sandbox for the first time discovers it. Discoveries and missions give XP, and leveling up unlocks bigger toys (TNT, lasers, black holes, a nuke). Missions rotate and scale with your level, and they start with a short tutorial chain.
• Juice. A bloom/glow layer, things glowing when hot, screen shake, a flash for big blasts, blast popups ("KABOOM!"), a combo meter with bonus XP, toasts, a confetti level-up screen and a soft generative soundtrack.
• Tools. Circle, square, line and spray brushes. Mix, heat and cool tools. Select with copy, cut, fill, delete and stamp. Zoom and pan, an eyedropper, undo, ambient temperature, simulation speed (up to 4x) and four canvas sizes. Saving and loading creations, and the canvas autosaves.
• Responsive. Desktop has a three-panel layout. Phones (portrait and landscape) get a compact toolbar and a horizontally scrolling palette. Touch works through pointer events.
• Performance. Typed-array simulation (about 2.5 ms per tick for 42k cells), bloom done in JS on downsampled buffers, and the glow switches off automatically on slow devices.

Controls

Input	Action
Left click / touch	Draw
Right click	Erase
Middle click / P	Pick the element under the cursor
Scroll, [ ]	Brush size
Ctrl + scroll	Zoom (drag with the Zoom tool to pan)
Space	Pause
Ctrl + Z	Undo
1-4	Circle / Square / Line / Spray
M H C	Mix / Heat / Cool tools
E	Eraser

CrazyGames integration (js/platform.js)

• Loads SDK v3 (https://sdk.crazygames.com/crazygames-sdk-v3.js) only when the game is running on a CrazyGames domain (or with ?cg in the URL), then calls SDK.init(). Other hosts skip it and boot instantly.
• Calls loadingStart / loadingStop around boot.
• Calls gameplayStart on the first interaction and gameplayStop while menus or modals are open.
• Calls happytime() on discoveries and level-ups.
• Midgame ad on Clear canvas, at most once every 3 minutes. Audio is muted while the ad plays.
• Rewarded ads: "Unlock now" on a level- or discovery-locked element's card, and +75 atoms in Shop → Free atoms (3-minute cooldown).
• Progress and the canvas are saved through SDK.data on CrazyGames, or localStorage when the game runs standalone.
• Every SDK call is wrapped, so the game runs offline or off-platform with no changes.

To submit, zip the folder contents (index.html, css/, js/, assets/) and upload the zip.

Project layout

index.html
css/style.css
js/elements.js   element definitions + lookup tables
js/sim.js        simulation (movement, heat, reactions, electricity, explosions, particles)
js/render.js     ImageData renderer + bloom
js/audio.js      synthesized SFX + generative music
js/platform.js   CrazyGames SDK wrapper / storage
js/progress.js   XP, levels, discoveries, missions
js/icons.js      inline SVG icons
js/ui.js         panels, palette, input, camera, modals, toasts
js/main.js       boot, starter scene, main loop
assets/fonts/    Silkscreen + Pixelify Sans (SIL Open Font License)

Credits

Fonts: Silkscreen by Jason Kottke and Pixelify Sans by Stefie Justprince, both under the SIL Open Font License 1.1.