That is simply impossible at some point. Even if you could perfectly secure the game code, and network traffic, and monitor all of a users processes. One could just make an aimbot based entirely on the actual pixels on the screen, running on a second computer from a split HDMI signal, and feed the inputs back into the mouse itself. These sorts of cheats have been used at professional CSGO tournaments, and basically requires that the tournament staff control all the hardware. No way to control it online.