Kaiju City Smash

Kaiju City Smash lets you be the giant monster. Stomp, punch and tail-swipe through a living city, toss cars, swat helicopters and fire a Rage Beam that slices through whole blocks. It runs in a browser tab with nothing to install.

What’s in it

• Three single-player modes. Versus AI against up to three rival kaiju, a two-minute Score Attack, and Survival against waves of helicopters and tanks.
• Online 1v1. One player hosts and gets a five-letter room code or an invite link. The other joins. If someone drops out, an AI takes over their kaiju so the match can finish.
• Local versus. Two to four players share one keyboard, each with their own keys.
• Four kaiju and five cities, from a rain-slick neon downtown to a snowy old town on a frozen river.
• Power-ups, bounty buildings, twelve achievements, unlockable skins and a photo mode.

The interesting engineering

• Online play without a game server. Matches are peer-to-peer over WebRTC. A free broker only introduces the two browsers, and after that the game traffic goes directly between them. That keeps the running cost at zero.
• Four players, one keyboard. Most keyboards drop keypresses when too many keys are held at once. Each of the four players gets their own cluster of keys, spread across the board.
• Destruction that scores. Taller buildings score more, landmarks pay double, and chained smashes build a combo. Big collapses trigger slow motion.
• A low-graphics mode for slower machines, so the game stays playable on an older laptop.

What I learned

Multiplayer changes everything about a small game, including who you can show it to. A room code is the lowest-friction invite I could find: no accounts, no friends list, just five letters. I shipped Kaiju through the same pipeline as every game in Play Arcade.