holy shit.... this is a tough one....
I honestly think it may've taken me about 15 years of gaming to accomplish what this thread's asking, and I'm pretty sure I did it with GTA V when it first came out. I remember looking up cheat codes, finding out you couldn't cheat for money and thinking "well, fuck it, then.." Seriously, money is the only thing that's hard to come by early on in GTA V, but that game is fun as shit even without cheat codes. I definitely cheated on all the other GTAs, though, and there's a ridiculous amount of games that I haven't cheated on that I also just never finished.
Also, if looking up shit in an online walkthrough is cheating.... fuck me, I cheat every time it takes more than 30min to figure some shit out, sometimes less time than that.
[EDIT: Wait, no! I finished the fuck out of both Star Ocean: The Second Story and Chrono Cross, and I'm pretty sure I remember being a start-to-finish fuckin' savage throughout the first couple Spyro the Dragon games. Final Fantasy was really my shit growing up, but I honestly don't think one's ever held my interest all the way throughout the end of any of the games.]