Classic: Derp Derp Derp?
Most examples of letting the AI cheat are above and beyond the call of duty, or even self-hating challenge for any gamer.
You folks throw around Mario Kart. I've always enjoyed the series in the SNES/N64 days, but put me in Double Dash and my eyes will turn comically blood red. And I bring it up all the fucking time, but try a Pokemon game's optional, end game shit. It's such a perfect, textbook example of sloppy AI programming.
There's an ending bracket of trainers in Battle Revolution that is evenly split between
interesting teams that use strategy alone to offer you challenge, and flat-out cheating bullshit cocksuckers. How insulting and lazy on the part of the programmers, to even bother to show us that they can do the AI properly and then to say "Fuck it, go fight a guy with legendaries who directly reads your data input."
I mark a colossal difference between the computer flat out cheating(10% proc rate becomes 100%, Blue Shells never fail to appear, etc) and added challenge.
If you wanna see added challenge done right and wrong, I recently beat God of War 2. There is a huge gauntlet of every monster in the game near the last Sister of Fate, and for a second I thought it was cheating pretty readily. Everytime I got to the Medusa wave, I'd get petrified a split second before a Siren's bolt hit me. On about my 4th try, I just abused the ever loving hell out of Titan's Rage and the randomly spawning separators. It was challenging and refreshing.
A bad example? The third part of the Ares fight in GoW1. Notable because the computer isn't even cheating. They just take away
all of your toys and tell you to win a duel with big-slow-stupid-strong-sword. It wasn't particularly fun and I didn't feel challenged after slogging through it. In fact, they undo this at the end of GoW2 and the difference is like night and day.
Maybe it's just me being a whiny git. It's a colossal pet peeve of mine for luck-based events to occur endlessly against my favor(cut me a break) or for the scenario in a game to be stacked so blatantly against you that the only way to win is via a miracle. I've never mastered Grand Theft Auto: Vice City because of that one retarded fucking racing mission where you have to beat the driver for the Bank Heist, and you're shackled with Two Stars and a Shitty Car while he has perfect driving AI and if he gets off screen, ignores all obstacles.
Nine times out of ten, the Computer AI does not need to cheat. He usually gets advantages you can only dream of, and it's often the whole draw of the gameplay that you are trying to defeat a horrifying, ridiculously powerful force by your lonesome. The Strider Finale at the end of HL2: Episode 2 was good because I was offered a metric fuckton of interesting tools and methods to deal with my foes, and probably would've been really piss poor if my enemies got to cheat on top of being an army fighting a single man with some amazing toys.