The world

The simulation is pure functions with no input or output. Every one of them takes state in and returns new state plus a list of events. That is what makes the rules testable and what makes them the same rules for everybody.

Units are metres, seconds and radians. The tick is 50 milliseconds.

The city

The map is generated from a seed with a seeded random number generator, so the server and the client build the same town from the same JSON. It is served at GET /api/world/map with a version, and it is public because the client has to draw it.

• 12 by 12 lots of 16 metres with 8 metre streets: a 288 metre square, origin at the centre, y pointing up.
• Each lot is empty, a park, or a building with a type, a height and a box.
• Fixed places: the office, which is the quest board and the spawn, the shop, four landmarks, eight courier points, and patrol waypoint loops for the drones that run along the streets at 6 metres up.

Everything the client needs to draw the block and the server needs to collide against is in that JSON. Nothing else is hardcoded on either side.

Players

A player is a position, a heading, a velocity, a shield from 0 to 3, a downed timer, the time of their last shot and their gear.

Movement arrives as an intent: a direction, never a position. Whatever vector turns up is normalised, so asking to move 50 units becomes a single unit step. The server integrates at 6 m/s, or 7 with the sprint gear, then slides the body along building boxes by resolving one axis at a time, then clamps to the map bounds. A player can never end a tick inside a building, and a long tick is capped so nobody crosses a wall in one jump.

Shield runs the damage model. A bolt hit costs one bar. A bar comes back every 8 seconds without a hit. At zero you are downed for 3 seconds and respawn at the office with a full shield. Quest progress is kept.

Drones

A drone has 3 hit points and three states: patrol, engage, dead.

• Patrol: 3 m/s along its waypoint loop.
• Engage: a player inside 25 metres pulls it in, and so does any player who shoots it from as far as 60 metres; it then holds that target for at least 6 seconds. It circles the player at 12 metres and fires a bolt every 2 seconds.
• The 10 metres around the office is a safe zone: no drone targets or fires at a player there, and a bolt that crosses into it dies. You can still shoot out of it.
• A room holds at most 12 live drones, with one respawn every 15 seconds at a random point on a loop.

Bolts

A bolt is a position and a velocity with an owner and a birth time. It flies at 18 m/s in a straight line toward where its target will be, leading a walking player by their current speed over the flight time, and it dies after 3 seconds or on impact. Changing direction after the shot still dodges it. Impact is a sphere against a capsule of radius 0.5 and height 1.8, tested against each player. Bolts do not hit other players' bodies as damage: there is no player versus player.

Shooting

A fire intent is a heading and a pitch, at most 4 a second on the MK1 blaster or 6 on the MK2. The shot is hitscan from the server's copy of your position at eye height, along the aim direction, out to 60 metres, with aim assist: the nearest live drone inside a 12 degree cone counts as hit. A hit costs one hit point, and the player with the most damage on a drone gets the kill.

The socket's own budget of 8 fire messages a second sits above the simulation's 4 on purpose. The budget stops a client spending the server's time asking. The simulation decides what actually fired.

Interacting

interact names a place, never a position: the office, the shop, a pickup, a delivery, or one of the four landmarks. The server measures from its own copy of where you are and refuses anything past 2.5 metres.

Events

Each function returns events alongside the new state: hit, kill, downed, respawn, pickup, deliver, landmark, spawn. Those are what the quest engine reads, and they are produced by the server, never sent in.

What the tests hold to

The simulation is covered by property tests, not just examples: no player is ever inside a building after any sequence of inputs, speed never goes above the cap, fire rate never goes above the cap, the drone count never goes above six, a dead drone never deals damage, and kill credit always goes to the top damage dealer.