The bots for custom games in League of Legends (especially before the recent release of Co-Op VS AI where they knew more people would be playing against them now) cheat their ass off. To get better stats, you have to buy items, which you do by getting gold from kills and just automatically over time. To get your full build of 6 items, it usually takes 35-45 minutes unless you get a lot of kills early. The bots automatically have their entire build at 30 minutes. They can also magically see you while you should be in stealth. The item thing is largely speculation because the bot mode is only a few weeks old, but I've been standing in brush (which stealths you completely unless there's an enemy in the same brush) and a bot walks up, hesitates for a second, then turns and unloads a metric fuckton of damage on my face. There's also the matter of how the bots having (even on beginner) far above human reflexes which makes the bots that play high-damage characters very dangerous, but that's not exactly cheating.