Why is it not more common to implement anti-cheat on the server instead of the client? Is that not more secure? Couldn’t the server just check what vision a player should have and not provide any other information to prevent wallhacks or maphacks? Or check how fast it is possible to move to prevent speedhacks? Aimbot is a bit harder to detect I guess but what about the other ones?
Client Side Prediction in combination with Server Authoritative Calculation should always be the correct option.
Basically, both the server and the client do the same calculation to see if a bullet hits. Then the server sees the client data and checks if it matches what the server calculated. If it does, then it ignores the client data and continues, otherwise it sends the correct data to overwrite the client. While the client waits for the server to check the data and send it back, it calculates the next frame based on previous server data such as previous enemy velocity, look angle, etc. The client is always slightly ahead of the server, but as long as the ping is low this isn’t a problem (depends on network data bandwidth, but usually anything below 150ms ping is not really noticeable, as the ping from your eyes to your brain processing it, then reacting to what you saw is between 150ms-300ms.)
This feels bad for players with bad ping, but it doesn’t have a negative effect on anyone else except cheaters that can no longer shoot you through walls or make impossible movements. And both of these are usually the fault of the client, as choosing a server with lower ping or simply not cheating will fix the problem immediately.
Client Authoritative Calculation, where the client tells the server the data to send other players, should never be used in a game where cheating would be a severe negative impact on the game, such as a PvP shooter.