What you cannot build yet

Every limit below is a limit of the engine as it stands, not of your approach. Each one is cheap to hit and expensive to discover halfway through a build.

No shooting, and no hitting a player with a ray

spatial::raycast deliberately excludes character bodies. Rays see map geometry and the collision proxies of archetypes flagged interact or contact — nothing else. There is also no health anywhere in the engine.

So: no hitscan weapons, no melee that resolves against a player, no deathmatch. What does work is a ray toward a player’s position, which tells you whether the map occludes them — enough for line-of-sight, hide-and-seek and vision cones. The watchman reference mod is built on exactly that.

Proximity, not player-to-player touch

Contact events fire for archetypes you flagged, and on-contact tells you when a player touched one of them. There is no player-to-player contact event, because neither party is a flagged entity.

Tag games are still easy: compare body positions each tick. Distance is a subtraction, and get-component on transform gives you the numbers.

One input action, and it is a debug key

There is no input system for mods. Exactly one action reaches client mods — the name echo, sent when F is pressed — and every client mod sees it. You cannot bind a key, name an action, or read movement input.

Design around it: use trigger volumes for “do a thing here” and interact (E) for “use this object”, both of which are real mechanisms.

Elimination has no spectator

You cannot despawn your own body, and there is exactly one camera which is a child of the body — so a player without a body sees black rather than the world.

“Eliminated” therefore has to mean moved: teleport them to a pen, a balcony, a jail. In practice that plays better anyway, because they can watch and heckle.

UI is one line of text

The whole client-side presentation surface is ui::set-overlay-text. No panels, no images, no layout, no input widgets. A scoreboard is a formatted string.

No items, no attachments

There is no inventory, no held item, and no way to attach one entity to another. A “carried” object can only be faked by moving it to follow its owner each tick.

No persistence, no sound

Nothing a mod writes survives the session; there is no save API. There is no audio API at all.

Cross-mod reach is bytes only

You cannot get a handle to another mod’s entity — find is scoped to your own, and a ray that hits a foreign entity reports the geometry without a handle. Mods cooperate by exchanging byte payloads over signals. That is a deliberate boundary, not a gap: a handle is permission to mutate.

What this leaves, concretely

Plenty, and more than it sounds: race and parkour courses, king-of-the-hill, tag and infection, hide-and-seek with real occlusion, red-light/green-light, floor-is-lava, puzzle rooms, trigger-driven traps, anything built from moving props and per-player text.

The common shape is: watch positions, move things, recolour things, tell people what happened.