How do they work? I know that in a game (Red Dead Redemption 2, for example) cheaters have infinite health and so forth. How? The server is responsible for validating all actions performed by players to prevent cheating, such as verifying movement, health, ammunition, and other game variables. It is not supposed to accept health values sent by the client without verifying against expected game logic. The server is the authoritative source. It is not supposed to rely on the client for authoritative game state, and if it does, it is fundamentally and terribly flawed.