Complete Full Game Download Halo 2

Opinion: Synchronous RTS Engines 2: Sync Harder

Game run fully in sync. Multiplayer games are fully peer-to-peer. There are two layers, Simulation and User. Sim Layer runs at a fixed 10 frames per second. Sim Layer includes everything important – physics, ai, movement, etc. User Layer runs freely up to 60 frames per second. User Layer includes UI, animation, and other strictly visual elements. All clients run 100percent identical simulation layers. Only input commands are sent over the network. The game is fully deterministic to allow each client to update based only on input. If that's too much to keep in the front lobes at once, then I recommend re-reading the original post. One area I glossed over was how command messages are handled across the network. Luckily, I work with the person who wrote it, William Howe-Lott, so I asked for details! Player input is handled in the form of commands to groups of units. The command (attack, move, stop, etc) for a group of units is bundled up and sent across the network to all other players. The message defines a Sim Tick slightly in the future to execute it on due to the synchronous engine. . Assume four players A, B, C, and D. Player A issues an attack command sometime during Sim Tick 7. Player A sends the command to player B, C, and D to execute on Sim Tick 11. Player B sends an acknowledgement, an Ack, to player A to say that they got it. Player B also sends a message to players C and D – an AckAck for lack of a better term – to tell them that they got player A's input. Players C and D do the same thing. Each player will only process a command when every An alternative method, and popular suggestion, would be to process a tick as soon as you have commands for all other players. There'd be no need to wait on Acks or AckAcks. As soon as Player B has messages from players A (attack), C (empty), and D (empty) it's good to go. This could work, but has a nasty edge case. Imagine that player A sends an attack command for Sim Tick 11 to players B and C and then disconnects. Player D is stuck while players B and C processed Sim Tick 11 and moved on to 12. This is recoverable as player B or C could send player A's command to player D. This would allow player D to execute Sim Tick 11 and then everyone can boot player A from the game and carry on. It can become pretty messy. Two of the most popular questions were on the topic of recovering from a game disconnect or from a desync. Let's look at the disconnect case first.