Slordax: The Unknown Enemy (id Software/Softdisk 1991)

This was id Software's first game to feature smooth background scrolling on PC. It was published shortly after the first Commander Keen trilogy but was in development first.
On seeing this game, John Romero realised the potential of PC games, and also the potential of John Carmack's programming skills.
This lead to the famous "Dangerous Dave in Copyright Infringement" demo that Carmack created for Romero to show off what he could do to incorporate smooth horizontal scrolling into PC games.

[@brgphotography]

That's a really interesting fact. I didn't know that. But I guess since Commander Keen was released first, it's still considered the first PC with scrolling.

[@cunningmunki]

Yeah, they rushed out the first Commander Keen trilogy in just a couple of months so that they could release a game with the smooth scrolling feature under their new publisher rather than Softdisk (since they knew it would be a big deal once other developers saw what they were capable of).
It reminds me a bit of when the Stamper brothers delayed the release of Knight Lore on the ZX Spectrum because they knew the impact it would have.
I didn't know about Slordax until reading John Romero's excellent "Doom Guy" autobiography.

[@brgphotography]

I wasn't aware of Romeo's autobiography! I'll have to pick that up. Especially since I've read Masters of Doom like 3 times! @@cunningmunki

[@brgphotography]

@@cunningmunki I just picked up DOOM GUY. Can't wait to start reading it!