Here is the full list of all 65 Doom 3: BFG Edition achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Complete any DOOM II level with 100% kills, items, and secrets in single player
Complete all levels in 'DOOM II: No Rest for the Living' in single player
Find a BFG in DOOM II single player
Complete any DOOM II level in single player
Find a secret area of a DOOM II level in single player
Complete DOOM Episode 3 on 'Hurt Me Plenty' or higher in single player
Complete the Lost Mission campaign on Recruit
Complete the Lost Mission campaign on Marine
Find the RAGE logo in the Lost Mission
Collect every PDA in the Lost Mission campaign
Get 2 demons to fight each other in DOOM 3, RoE, or Lost Mission
Complete any level in Ultimate DOOM in singleplayer
Complete any DOOM level with 100% kills, items, and secrets in single player
Complete the DOOM 3 single player campaign on Recruit
Complete the DOOM 3 single player campaign on Marine
Complete the DOOM 3 single player campaign on Veteran
Complete the DOOM 3 single player campaign on Nightmare
Collect every PDA in DOOM 3
Find all video logs in DOOM 3
Kill an enemy with 1 health remaining in DOOM 3, RoE, or Lost Mission
Open all storage lockers in DOOM 3
Kill 20 enemies with the fists/melee hands in DOOM 3
Kill the scientist trapped next to the Reactor Control Room in DOOM 3
Kill 2 Imps with one shotgun blast in DOOM 3, RoE, or Lost Mission
Score 25000 on Super Turbo Turkey Puncher 3 in DOOM 3 or RoE
Blow up 50 barrels in the DOOM 3, RoE, or Lost Mission campaigns
Get the BFG-9000 from Security Chief's office in DOOM 3
Complete a level without taking any damage in DOOM 3, RoE, or Lost Mission (except Mars City)
Complete the DOOM 3 single player campaign in 10 hours or less
Defeat the Vagary boss in DOOM 3
Defeat Guardian boss in DOOM 3
Defeat Sabaoth boss in DOOM 3
Defeat Cyberdemon boss in DOOM 3
Keep a Sentry Bot alive to its destination in DOOM 3, RoE, or Lost Mission (except Mars City)
Use the chainsaw to kill 20 enemies in DOOM 3
Find the id logo secret room in DOOM 3
Find the bloody handiwork of Betruger (in Delta 4 Hallway) in DOOM 3
Use the Soul Cube to defeat 20 enemies in DOOM 3
Complete the RoE campaign on Recruit
Complete the RoE campaign on Marine
Complete the RoE campaign on Veteran
Complete the RoE campaign on Nightmare
Collect every PDA in the RoE campaign
Kill 5 enemies at once while in Hell Time in RoE
Defeat the Helltime Hunter in RoE
Defeat the Berserk Hunter in RoE
Defeat the Invulnerability Hunter in RoE
Defeat the Maledict boss in RoE
Kill 20 enemies with projectiles launched from the Grabber in RoE
Use the Artifact with Berserk ability to punch out 20 enemies in RoE
Complete the Lost Mission campaign on Veteran
Complete the Lost Mission campaign on Nightmare
Kill an enemy player by jumping into a teleporter after them in DOOM 3 Multiplayer
Catch an enemy player in the Reactor of Frag Chamber in DOOM 3 Multiplayer
Kill 5 enemy players while using Invisibility in DOOM 3 Multiplayer
Complete a DOOM 3 Multiplayer match without dying
Use Berserk to kill a player in DOOM 3 Multiplayer
Kill two enemies in the same room with a rocket in DOOM 3 Multiplayer
Complete DOOM Episode 1 on 'Hurt Me Plenty' or higher in single player
Complete DOOM Episode 2 on 'Hurt Me Plenty' or higher in single player
Complete DOOM Episode 4 on 'Hurt Me Plenty' or higher in single player
Complete all DOOM levels on 'Ultra-Violence' or higher in single player
Complete any DOOM level on 'Nightmare' in single player
Complete all levels in 'DOOM II: Hell on Earth' in single player
Complete all 'DOOM II: Hell on Earth' levels on 'Ultra-Violence' or higher in single player