Kind of... I didn't really have the time, so to beat Gears of War 2 on the hardest difficulty, I was playing as player 1 on casual, though when my brother was free he took control of player 1, while player 2 played on hardcore, but I could have beat it on my own, it was just a matter of saving time
I did download Dash for Destruction, which feels like cheating, but it was quite fun for the half and hour it took to complete
I haven't actually cheated properly, but with Infinite Undiscovery's play for 40 hours achievement, I did leave my Xbox on, though I still haven't finished that game
I always use guides, I don't really want to waste time, because I have a lot of games to play!!