Full Synchronization with Input Lag

Lockstep

  • "The inputs of both players are exchanged with each other, so both players will be running the same simulation."

  • A stricter synchronization method where all machines involved in the system must process the same inputs at the same time before advancing.

  • Requirements :

    • The game must be absolutely deterministic .

  • Advantages :

    • Keeps all players perfectly synchronized.

    • Prevents cheating that could occur in client-authoritative netcodes.

    • Uses low bandwidth, as only inputs are sent.

  • Disadvantages :

    • Can be affected by input lag , since all players must wait for each other's inputs before advancing.

    • If one player has high latency, all others are impacted (the classic "slowdown" problem in old RTS games).

    • Harder to scale for games with many simultaneous players.

  • Uses :

    • RTS (Real-Time Strategy):

      • StarCraft, Age of Empires

    • TBS (Turn-Based Strategy):

      • XCOM Multiplayer, Civilization

    • Physics-Based Deterministic Games:

      • Games that require identical simulations on all machines.