Super Mario 64 again :P
Killer Instinct on the SNES, followed closely by Top Gear.
I think the first game I actually beat by myself was breath of fire on snes
First game I ever beat was in kindergarten or first grade. Ham Ham Heartbreak for gameboy. Still have it and beaten it multiple times... it is my childhood. Lol
The first game I ever beat was Super Mario 64. I think I was 6-7 when it happened. Lol after I beat it I started crying because I did not want the game to end. XD
Sonic 2 for me, Sanic along with other genesis stuff like streets of rage 2, altered beast, mortal kombat, etc were literally the first video games I've played in general.
I can't really remember clearly, though I guess Mario Kart 64, if you can count that?
If you're talking about a game with a specific main campaign, I really don't know...
Probably this one but the final boss was hella hard cuz u had to repeat a lot of bosses in order to defeat the last one, if u died u had to repeat it all over again. Plus even if u got to the final boss (which was easy), problem was... you had not much HP and power left so. RIP.
The very first game which I was able to complete without resorting to any cheats was the PC-ported version of the arcade classic Golden Axe.
I was 8 years old and it took me an entire year to achieve the victory in that game because there was no way to write any savedata in the middle of the playthrough and because back in those days my mother would never allow me to sit at the computer for longer than 1 hour per day and I didn't have my own separate computer for obvious reasons (typical 8 year-olds don't earn any incomes). Furthermore, I was unaware that it was possible to modify the game's settings and extend the lifemeter and that it wasn't a cheatcode.
So yeah, when I finally achieved that victory I felt like a true champion, like a receiver of some kind of noteworthy trophy, due to the all the obstacles and limitations and conditions which I just mentioned.