A to Z Challenge: Doom

 The original Doom came a couple years after id Software's popular first-person shooter Wolfenstein 3D.  This screenshot is from one of the console versions where they pixelated a lot of the Nazi stuff and showed less blood:

While that game was set in Nazi Germany, Doom was set in the future on Mars.  You play as a Marine who has to clear out a bunch of demons who have suddenly appeared on the planet.  The gameplay is largely the same as you choose from different weapons and go around in first-person to shoot the monsters.  And a lot of the gameplay can be just feeling around for secret doors to find keys to open other doors or maybe other treasures.  It can be a real pain.

You start with a pistol and hand spike and then can get a chainsaw, shotgun, Gatling gun, rocket launcher, plasma rifle, and the BFG:  Big Fucking Gun!  The BFG shoots a green energy ball that kills or does major damage to a large area, but the downside is it needs time to recharge and has limited ammo and isn't something you can really use up-close, so most of the time you'd want to use the plasma rifle or the Gatling gun or the shotgun, though the latter has less ammo.

The final level can be kind of nerve-wracking as there's an anteroom and then this big room with a giant cyborg Minotaur who shoots missiles.  The nerve-wracking thing is unless you cheat, you have to kind of dance around and sometimes go back into the anteroom to find more ammo or health packs and then you have to worry where the cyborg Minotaur went; sometimes you'd just hear the shrieking and clanking of his robotic joints getting closer and closer...

Though really I think you could just slip past that dude, shoot the heads hanging up in the next room, and jump into the warp gate or whatever to end the game if you want to be a chicken.  If you aren't quick enough or the Minotaur isn't far enough away, he could come back to blow the hell out of you with missiles.  If you use the "god code" to cheat you don't really have to worry as you're invulnerable and can get unlimited ammo to just go up to him and blast him with BFG or ion bursts or rockets until he dies.

The sequel Doom II:  Hell on Earth takes you to Earth, though there's really nothing that recognizable as being on Earth.  You go around to more levels and fight more enemies.  I don't think you really even got new weapons or anything so it was more of an expansion pack than a whole new game.

One of the neat things was you could create "WAD" files that let you customize the weapons and stuff in the game.  If you were a really good artist/programmer you could probably do all sorts of neat things, but I just customized the weapons slightly to correspond to some Transformers fanfics I did.

The first one I did corresponded with Transformers: Xenophobia and an original character I created called Ambush.  He was basically a Special Forces type who turned into a Hummer or something like that.  His weapon of choice was a shotgun, so I recolored the shotgun to go with his green paint scheme.  I'm not sure I changed the other weapons all that much.  

I did another one for The Skyfire Adventures where in the first story the Maximal Skyfire, formerly the Autobot Jetfire, fights demons on some planet.  I forget which weapon I made Skyfire's; it might have been the plasma rifle. 

The other one I did was a Beast Wars one for a character I created called Outfox who was, of course, a fox.  His tail would have popped off to become a gun.  I think again I used the shotgun as the model for it.  I think I did a little customizing to make the Gatling gun like Rhinox's and the missile launcher like Optimus Primal's.  If I'd really had any skills for drawing and stuff, I probably could have made the chainsaw Dinobot's sword, the pistol Rattrap's gun, the plasma rifle Cheetor/Tigatron's gut gun, and maybe done something with the BFG.

I have no idea if I have any of those files saved anywhere or if I could still use them somehow.

I got Wolfenstein, Doom, and Doom II in a bundle from GOG.com a few years ago and found they weren't as exciting as I remembered.  Wolfenstein especially there's a lot of wandering around feeling for doors to find keys and treasure.  And a couple of spots in each game it can be confusing to know what you're supposed to do so I wound up wandering around and around until I had to go look up a video on YouTube to find out what I needed to do.  Shooter games are a lot more fun when you're, you know, shooting stuff.