Hypersomnia

Hypersomnia is a top-down competitive shooter that borrows its economy and its round structure from Counter-Strike and then does something much stranger with the networking. It is free, AGPL-3.0, and developed entirely in the open by Patryk Czachurski and a small collective around him.

Moment to moment it is a bomb-defusal game seen from directly above. Two factions, Metropolis and Resistance, buy weapons between rounds from a shop with real opportunity cost, then fight over a site. Because you are looking down, the information game is inverted from an FPS: you can see the whole room you are standing in but nothing through a doorway, so peeking is a commitment and sound tells you more than sight does. Gunfights resolve in a fraction of a second. Recoil climbs, spread matters, and a shotgun round at close range is simply the end of the conversation. There is a knife, there are grenades that bounce, and there is a satisfying amount of physics debris that gets thrown around when things go off.

The technical story is the one people talk about. Rather than replicating world state, the server transmits only player inputs — "moved here, pressed this" — and every client simulates the rest deterministically. The result is that traffic scales with the number of players rather than the number of objects: two characters in a map full of dynamic crates cost roughly 5 KB/s at a 60 Hz tick. When a new client joins, already-connected clients rebuild their physics state from scratch so everyone's simulation stays bit-identical. That determinism is also what makes the browser client possible — you can host a server in a browser tab and have native clients connect to it.

The surrounding infrastructure is unusually complete for a free project. There are official ranked and casual server instances per region, a server browser, spectating, a built-in level editor, and custom maps that download automatically over HTTPS when you connect to a server running one — so a group can play an arena nobody else has installed. Ranked has a rating that is shared between the Steam and web versions if you link a Discord account. There is a full single-elimination tournament mode the dedicated server runs on its own, spawning one instance per match and advancing the bracket without anybody managing it by hand.

That dedicated server is a separate headless binary — under 30 MB — which is why PlayBound can host private rooms for it on request rather than relying on someone's home connection accepting inbound UDP.

One honest limitation: there is no gamepad support. Nothing in the source or the default configuration reads a joystick, so this is mouse and keyboard only, and we have deliberately not tagged it for controllers.