Arenas

Players fight in real time with the abilities of the class they pick, and the hub referees every hit: the shape of a brawler, an arena shooter, a skirmish. Clients report where their player is (move { x, z }, a few times a second) and the movement warden keeps what the class's speed allows (a move too fast is cut short, a jump refused, and a run of refusals removes the player); a cast is checked for its cooldown, resource and range and lands as the hub decides: a hit-scan strike on the fighter nearest its aim, a projectile the hub flies a tick at a time, an area that goes off after its delay. Statuses tick, the fallen come back after respawn_ms, and the first to kill_target kills (or the most kills when the time runs out) wins. Positions are the arena's own units, (0, 0) to (width, depth). With an anchor (the chunk the arena is at), casts, impacts and the warden's flags also go out as realtime events 94 and 95.

Starter: crate arena, node type arena, keyed by the arena (a match). Module: kit.arenas.arena(key) in CrowdyJS, arenas().arena(key) in CrowdyCPP, kit.arenas.arena(key) in CrowdyPy.

Endpoints

Endpoint	Who	What
join { class }, leave	players	bad_request (not a class), full, started
start	the first to join, or a developer	forbidden, not_ready (one fighter), started
move { x, z }	fighters	Answers [x, z], the position kept: forbidden (removed), conflict (down)
cast { ability, x, z }	fighters	Aimed at a point; answers whether a hit-scan strike hit at once: cooldown, insufficient, out_of_reach, not_found
state	anyone	The arena

Every change takes an action_id, answered once; refusals carry the codes above (see the protocol).

Topics

arena: snapshots up to five times a second (fighters with health, resource, statuses, kills and positions; projectiles; pending areas), and events (type: cast, impact, kill, respawn, violation, removed, finished).

Config

A type's seed (seed_b64 in the manifest, the same for every key) is the starter's JSON config; what it leaves out keeps its default. width and depth (40), spawns, the classes (the starter's are warrior and mage, each with its abilities), players_max, kill_target (10), duration_ms (5 min), respawn_ms, teleport, remove_after_strikes (8), anchor.

CrowdyJS

const arena = kit.arenas.arena(matchId);
arena.view.onEvent((e) => e.type === 'impact' && flash(e));
await arena.watch();
await arena.join('mage');
setInterval(() => arena.move(me.x, me.z).then(([x, z]) => snapTo(x, z)), 200);
await arena.cast('bolt', aim.x, aim.z);

CrowdyCPP

auto& arena = kit->arenas().arena(matchId);
arena.join("mage", [](crowdy::kit::KitReply) {});
// a few times a second:
arena.move(me.x, me.z, [&](crowdy::kit::KitReply r) {
  if (r.ok()) snapTo(r.value().at(0).asDouble(), r.value().at(1).asDouble());
});
arena.cast("bolt", aim.x, aim.z, [](crowdy::kit::KitReply r) {
  if (r.code() == "cooldown") showCooldown();
});
game.poll(); // replies, topic messages and mirror changes arrive here

CrowdyPy

arena = kit.arenas.arena(match_id)
await arena.watch()
await arena.join("mage")
x, z = await arena.move(me.x, me.z)
await arena.cast("bolt", aim.x, aim.z)