Never been very competitive in games, so cheating to win against other people was never something I've felt compelled to do.
But in single player games, all the time! XP earning multipliers in Pokémon, house ruling Arkham Horror so Investigators can interleave their Actions in any order, starting Sims with all the money! Editing a save file to resurrect that one NPC I might've killed for being too snarky in etc etc.
I wish I could cheat more in computer games, honestly!