Comment by tracker1

Lag is the biggest issue... even a local wifi connection vs wired can make a massive difference in terms of what's acceptable lag.

Of course, to TFA's point on network code... a lot of the issues in question could come down to checking for movements that exceed human... moving faster than the speed in game, or even twitch aiming movements faster than a mouse, or a consistent level of X accuracy in shooting over time. On the last part, I'm not sure if there might be some way to mask a user's hit zone, rendering and such so that an aim-bot thinks the foot is center-mass, etc. Or if it could be randomly shifted in a test scenario.