Virtuoso - Part 1 - Get your ass to Mars.
Virtuoso is an incredibly obscure shooter from 1994. Part of the reason it's so obscure is because it's terrible. And not even in a fun way. You're playing a rock star who is playing video games and there's three different video games he plays. The first one, which is fully covered in this episode, is "Mars" which totally wasn't made because Doom was released about six months before this game and was set there.
I had been considering doing a speed run of this game as part of my tendency to speed run really terrible games that no one should play and are a horrible idea to speed run anyway. The first episode actually isn't that bad in that regard and I think I could complete it in about twenty minutes with a bit of practice. The other two episodes... Well, let's say I've changed my mind on the speed run and the third episode is a major reason why.
I can think of one shooter (I'd call it an FPS but as you can see it's not really "first-person") I've played that is worse than this.