Hmm. Plenty of games allow you to have a pretty badass MC, but if I had to only pick one, I think my vote would go to the long-dead WiP A Hag Called Fate, where the MC is essentially the Big Bad’s Dragon (possibly with an agenda. Also possibly a literal dragon-person). The opening scene in particular really sells it perfectly, pitting you against the ragtag group of heroes at the beginning of their journey, full of hopes, dreams and protagonist gumption.
Unfortunately, the demo link doesn’t work anymore. I think the game went through a rewrite, with another demo under a new title, but from what I remember, it didn’t quite manage to catch the initial feeling I got the first time around.