I think everyone used cheat codes back in the day. Hardly any games ave them nowadays but back in the SNES, N64, and PS2 days (this is when they were becoming less frequent) I used a lot. You really can't play the old GTA games without using cheats. That's where the whole fun of those games come from. I remember my brother got the infinite ammo cheat from copying a tips and tricks book out of the grocery store and a lot of other ones too. I can't think of any others right now, but I'm sure we used more than just those.
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I didn't know KH II had cheat codes unless you meant he used a gameshark.