Rip & Tear: finish a level on Nightmare difficulty- done on the first map. I tried to get through at least the second too, but haven't been able to yet. Then I watched the world record Nightmare speed run on youtube and was dumbfounded by how bad I am at this game.
Superior Firepower: finish all levels on ultraviolence- overall not horrible. I can't really put down a particular level as the hardest
From Earth to Hell: finish all level of Doom 2: Hell on Earth- I went through this on ultraviolence straight off, since I'd played the game on the computer before. Although I don't recall if I'd beaten it legitimately before (I'm not great shooting with a keyboard and mouse, so I might've cheated or played through on a lower difficulty)
Doom 3: BFG Edition
Doomed Veteran: complete the Doom 3 campaign on veteran (hard) difficulty- I'd played this on the computer also, but this time I'm sure I'd beaten it on hard (legit) before, so I knew what was up. I was surprised how much easier some parts were then I remembered.
I Like to Watch: find all video disks in Doom 3- kind of surprised I got them all, figured I'd miss at least one
That Was Close: kill in enemy with 1 health remaining- got this in Alpha Labs 4. I was in a shootout with a security zombie and happened to win with 1 HP left.
Goody Finder: unlock all storage lockers in Doom 3- strangely, I distinctly remember opening another locker after I got this
Unarmed Bada__: kill 20 enemies with your fists- got this around 2/3 through the game, just punching zombies. I started out shooting them a couple times, then found out it only counts if you use only your hands.
To Be or Not to Be: kill the scientist in the reactor chamber- like, why is this an achievement?
Killing Time: score 25000 points in Super Mega Turkey Puncher 3- this was lame. You just have to spam RT until you get enough points
Boomtastic: destroy 50 barrels- got maybe 1/3 of the way through
Ready for Action: find the BFG in the Security Admin's office
Not a Scratch: finish a level without taking damage (except Mars City)- done in Mars City Underground (although it didn't count, it's apparently still Mars City), Communications Transfer, and Delta Labs 4 (wasn't going for it in the lab, it just happened). The ENPRO plant might've worked, too.
Sticky Situation: kill the Vagary in the Alpha Labs- I hate the first one of these things. There's hardly any room and you don't have great weapons. Fortunately, I had the secret plasma rifle and was able to take it after a couple tries.
Cookie Stealer: kill the Guardian- this thing is cool, although the battle was pretty simple. He (it?) did get me once, though.
You're Not my Boss: kill Sabaoth- I started out with a few rockets, then the soulcube, then a couple more rockets & it was done
Big Boy: kill the Cyberdemon- lame for a final battle. Every other boss killed me at least once except for him
Bot Buddy: keep a sentry alive until it reaches its docking point- got this at the first oppurtunity
Ripped: kill 20 enemies with the chainsaw- basically just let zombies walk right into the blade
All of Us: find the id secret room- can't say I found this alone; I looked it up back when I played on the computer
You Laugh, It Works: find Betruger's bloody handiwork in Delta Labs 4- I didn't even realize what I found. This popped up in the middle of a fight with a chainsaw zombie.
Turncoat: get two monsters to fight each other- done in Hell. I got an Imp to fireball a Hellknight. Surprisingly, the imp wasn't one-hit killed in the fight
Soulfood: kill 20 enemies with the soulcube- love this weapon. Have a feeling I'm going to love it even more when I have to depend on it for health in nightmare.l