Life of a shot

You aim at a soldier across a corridor and pull the trigger. Within a sixtieth of a second the simulation has decided where the bullet went, what it hit and what that did; a moment after that you see the flash, hear the shot and watch the body fall. This sheet follows that one bullet through every system it touches.

• The simulation decides
• The hit and what it does
• The adapter shows and sounds it

1. The trigger press waits for the next tick

   Your mouse click is read when the screen draws a frame, but nothing happens to the world yet. The press is queued as input, and the simulation picks it up at the start of its next tick. Every change to the world arrives this way, which is why the same inputs always produce the same game.

   Simulation and replay

2. The weapon checks, then fires

   During the tick's step for players and their weapons, the gun runs its fixed checks: is firing allowed, is it off cooldown, is it not overheated, has the barrel spun up. Then it pays one round from the magazine, or starts a reload if the magazine is empty.

   Weapons and projectiles

3. The shot is traced

   The shot starts at your eye, or at the gun's barrel if the body names its muzzles, steered onto whatever the crosshair is on. A barrel poking through a wall cannot shoot through it. A bullet is a line drawn at once: the simulation asks the world what that line meets first, and the answer comes from the level and from every body, down to the part of the body that was struck. A rocket or grenade would instead fly, fall and bounce, tick by tick, until it touched something or its fuse ran out.

   Bodies and collision

4. The hit goes through the damage door

   Every hurt in the engine passes through one door, in one fixed order. If the soldier were immune to bullets, nothing at all would happen: no blood, no sound. He is not, so a headshot bonus is added if the line struck his head, any effects on him scale the damage, his resistance to this kind of hurt applies, his armour takes its share, and his health drops.

   Damage

5. The body comes apart, or falls

   If the shot kills him, the gore system decides how. Only a hit that goes far enough past the killing point tears a body apart, and then the chunks fly away from the shooter in a fan, tumble, bounce, drip and settle. A lesser killing blow leaves a corpse. Either way, a wound bad enough throws a real blood patch onto the wall behind him, up to 12 metres away (as of 2026-10-22).

   Gore

6. Everyone nearby reacts

   A gunshot is an alarm. Enemies close enough hear it, even through walls, and farther ones hear it if they have a clear line to the sound; hearing it wakes them, sends them towards where it came from and makes them call their allies. A soldier who is hit but not killed is pointed at where the wound came from, may stagger, and turns on whoever shot him if he can see and reach them. If a game has switched dodging on, he may also sidestep the next round. These choices play out from the next tick.

   What enemies can do

7. Pulses carry the news across

   Each of these moments raised a pulse, a short report of what happened: shot fired, impact, damage, body torn apart. At the end of the frame the adapter receives them, in order. It never changes what the simulation decided; it only shows it.

   Simulation and replay

8. Flash, spray and mark

   The adapter looks up each pulse against its circumstances: whose body, which round, which surface. The muzzle flash leaves from the barrel and claims one of a fixed number of lights. The blood spray takes the soldier's own blood colour. If the bullet had missed, the wall it struck would get a mark chosen by round and surface, such as a bullet hole. The blood patch on the wall dries from glossy to matte over half a minute.

   Rendering and effects

9. Two sounds win a voice

   Your gun's own fire sound plays flat in your ears, with a small change of pitch so no two shots sound alike; the impact sound is chosen by the same lookup that chose the spray, so sound and picture agree. Both must win a voice from a limited budget, and a gunshot outranks footsteps, so a crowd's feet never cut it off.

   Audio

10. The body on screen

    Your gun kicks in its fire animation. The soldier's drawn body follows what the simulation decided: a corpse drops as a limp ragdoll, or the torn-off pieces tumble and come to rest on screen.

    Animation and bodies on screen

11. The counter drops by one

    On the heads-up display, the ammo reading falls by one round. Had you been the one shot, the screen would have flashed red.

    UI, HUD and in-world screens

Why it is split this way

Everything above the line of pulses happens inside the simulation, in one tick, the same way every time. Everything below it is presentation. Because the deciding half never waits on the drawing half, a slow frame on your screen cannot change where a bullet went, and a recording of the inputs replays the same fight.