If you’re into retro FPS gaming at all you should do yourself a favor and play Blood-- I think it’s where I learned the word akimbo, as there’s a powerup that lets you shoot double guns for awhile. That’s not why you should play it though; it’s a classic in its own right, and was built on the Build engine (along with Duke 3d and Shadow Warrior).

en.wikipedia.org/wiki/Blood_(video_game)