So many first person shooters are ruined by aimbots.
I loved Halo: Combat Evolved a long time ago, but at some point many people would start using aimbots and at that point the game was ruined for me.
I was the other one of the two people who played Halo 1 online. Alot of people don't even know the first game had online since it was PC only and not on the Xbox version. Great game, it had some huge maps. At least the sequels had a great run online, albeit on console.
Team Fortress 2 has plagues by aimbots for the past few years, yet VALVe have done practically nothing to aid the situation. VALVe are still raking in an income from Team Fortress 2 (via lootcrates and a PVE gamemode), yet nothing has been done to fix any of the issues in official VALVe servers.