Drawing — Pick a material from the toolbar, then click and drag on the canvas. The Brush slider sets your pour size. Solids paint dense; powders and liquids sprinkle.
The spouts — Two hoppers sit at the top of the screen; drag either left or right. The material spout endlessly pours whatever the Spout dropdown selects. The boulder spout drops heavy round boulders that roll downhill and crush soft material — set its drop rate with the Boulders slider (off by default).
Torch — One torch per click. It falls until it lands on a surface and burns forever — unless water touches it.
Zombies & Humans — One per click, ten max of each. Zombies chase and convert humans on touch, and claw through soft material and wood. Humans wander, climb over any wall, and swim on the surface of water. They flee zombies (but won't notice one behind a wall). They defend themselves: they pick up TNT, C4, gunpowder, and wood; bombers plant a trap that detonates when a zombie touches it; engineers carry wood toward a zombie and build a barricade in its path at double speed. They grab live grenades (freezing the fuse) to drop near a zombie with a fresh 5-second timer, plasma-cut through aluminum, and avoid fire. Acid melts both species; ice freezes them; fire makes them run until they burn up or reach water.
Gold & the cure — Drop gold coins anywhere; humans love it and rush to collect any they can see, with their coin count shown overhead. A human carrying 100+ coins becomes a healer: instead of fleeing, they march up to a zombie and turn it back into a human, spending 100 coins per cure. When a human dies, their gold spills where they fell.
Fireworks — Whenever fireworks are bursting anywhere on screen, every human stops to cheer and jump for joy.
Portal doors — Place them in linked pairs: click once to set the first door (it pulses while it waits), click again to set its partner. Any human or zombie that walks into one door instantly steps out of the other — great for shortcuts, loops, or funneling the undead somewhere nasty.
Grenade — Press and hold to set the fuse: every second held adds a second to the timer, up to 30. Release to drop it. Watch the countdown and the blinking light.
Heavy weapons — Nukes, the Disintegrator, and the dirt & plant balls are aimed artillery, Tank Wars style. Press and hold: drag left/right to set the angle, up/down to set the power — a dotted line previews the arc. Clicking the right half of the screen fires from the left edge, and vice versa. Release to fire.
Payloads — The 20kt nuke leaves a huge crater; the 5Mt erases most of the map — nothing survives, not even concrete. The Disintegrator bores branching, lightning-like tunnels through whatever it hits. Ball-o-Dirt and Ball-o-Plant swell a large ball of material into existence on impact. The Sonic Disruptor parachutes in above your click — when it lands, the screen strobes and the entire world collapses into a random loose powder. Its only counter: land it in acid and it simply melts.
Shortcuts — Space pauses, C clears, E erases, F goes fullscreen.