The reason is very simple: you will lose the cheating war, and after a short time, it will be nothing but a hacking orgy. FPS are just too easy to play for bots or "human enhancers", so no matter how you setup anti-cheat stuff, there's always a way to be better with a hack or aimbot.
Difficult games like Go or StarCraft, or games that focus on diplomacy, might be an idea for the long run. Just anything it's hard to program a bot for.
Cheating and bots are allowed for all but on server1 and server3 only knife and Grenades are avabile so cheating is pointless (skipping radar). Server2 = bots battles
I love strategy games. Another game that I'm going to do is just a strategy game