Fighting the hacks
First of all, admins, pure server settings will not fight OpenGL hacks. Don’t dismiss complaints of players cheating, especially when accompanied by screenshots (note to players: take many) and demos.
There are ways to counter-act the effectiveness of the cheats, even player ESP. First, all servers – no matter what the game mode – should have the killcam turned on. If the cheater’s moving around, doesn’t set up and takes a reflex shot against a tiny portion of your helmet the first time he sees it in a window, across a long distance, it’s a sign (though no guarantee) that he’s got a hack enabled. Killcam also spots the numerous players with the fog disabled – but again, there’s been discussion that different video cards have different levels of fog, so it’s not certainty. However, if the same person is taking too many long shots, there should be little doubt. Finally, killcam permits dead players to take screenshots if they think their death was suspicious.
Next tip for server admins – disable the team identification textures (the floating Axis and Allied icons above players.) When everyone is red and green, it becomes difficult to tell them apart at any appreciable distance. The fool running around shooting everything that moves may simply be trigger-happy, or maybe everyone looks the same to him.
League admins, get screenshots – and at least one with the console. Even though the hacks can be disabled, certain artifacts cannot. The screen gets brighter and the console looks very odd, with colors that simply aren’t supposed to be there. At least on my NVIDIA card.
Watch for players that are *too good*. This isn’t Quake; the separation of skill isn’t nearly as extreme. If someone goes 28-3 on a crowded Pavlov or POW camp in a team deathmatch
setting, you can bet he’s got a hack – especially on specialty servers that allow only one kind of weapon (be it all-sniper, all-rifle, all-SMG). It’s one thing to play cautious on search & destroy, getting 11 frags and 2 deaths, but people are a lot more aggressive on team deathmatch and the passive, careful players should die a lot more often unless they have a little bit of that old ESP going. Keep in mind that in different game modes there are different probable kill ratios. In deathmatch it's quite possible to have a 5:1 ratio on a map that isn't too crowded, or to win by 30 frags over your nearest competitor, as this demo of om|nightfall demonstrates.
In S&D you may find a player who went 20-2 by being careful. Don't be afraid to spectate their POV and watch for fishy behavior, but calling out "hax!" just because someone is better than you is disreputable.
Global spectator mode can allow teams to cheat while at LAN parties or cafes, but allowing players from both teams to spectate each other to look for cheaters is also important. It’s a judgment call, dependent mostly on which problem is more apparent on your specific server.
Finally, don’t forget that there are entire “clans” out there that specialize in cheating. Having spent a lot of time spectating with various modes on, I was shocked to discover not just how many players had the hack (about one in ten or twenty), but that certain servers would get infested by a group of friends who’d all have it on, and they’d dominate. So just because [CLAN]Doofus and [CLAN]Punk say that they see [CLAN]Dumbass’s screen and he’s not cheating, that doesn’t mean they’re telling the truth, even if they’re regulars on your server.