CHEATS NEVER PROSPER
Only a niche concern this, but still a potentially mind-breaking problem. See, Grand Theft Auto has lots of cheats - plenty of which change the way the world works around you. So, for instance, you can give all the pedestrians guns. Or you can make them try to kill each other. Or you can give them guns and make them try to kill each other. Fun, no?
Fun, but only so long as your savegame isn't corrupted, randomly, by using these codes. Or if you accidentally save the game with GTA III's 'Liberty City Survivor' cheat - ie, pedestrians shooting each other - activated. And then find you can't turn it off. Ever.
This happened to us at the very last mission. Since we couldn't turn off the cheat, we could never rescue Maria because the guards surrounding her (and anyone else nearby) always killed her first. So, with no uncorrupted savegames, we had to start again. From the very beginning. Damn you, Rockstar!