When Duke Nukem 3D burst onto the FPS scene in the Nineties, young CJ was a bit confused. This Duke wasn't the purple-shirted acrobat I'd known from Apogee Software's pair of platformers earlier that decade. He was brash, crude, and and didn't side-scroll anymore. It wasn't for me, so I moved on to other games. I still occasionally loaded up those earlier platformers though, wistfully remembering a time when Duke presumably used actual toilets when he needed to answer a call of nature.
Apogee were the dons of PC platforming back in the early to mid Nineties. I suspect that was partly down to people having easy access to the games they published through shareware, such as id Software's Commander Keen and Wolfenstein 3D. I can't even remember now if I ever actually owned the whole of 1991's Duke Nukem, but I played whatever portion I had repeatedly enough that it may as well have been a full game.
The platforming version of Duke Nukem was a little like Turrican and Mega Man. It's not easy to get hold of these days, but you can find the game on some abandonware sites if you choose to look around. It pit Duke against the evil Dr. Proton and various underlings, and you could somersault our surprisingly well-behaved hero around to collect a bunch of power-ups for his weapons. I like to imagine that Duke bashed his head on a particularly low ceiling towards the end of his platforming adventures, resulting in the embarrassing persona seen in his later games.