Here is the full list of all 80 Rise of the Triad achievements.
Complete E2L1 100%
Complete Episode 1 100%
Complete E1L4 100%
Eat 50 Meals
Complete E1L3 100%
Gib 2 Enemies with the Split Missile
Beat the Game on Easy Difficulty
Beat the Game on Medium Difficulty
Pick up the Doomstick for the first time
Run the Game with a Custom Mod or Map Installed
Complete E1L5 100%
Get "Ludicrous gibs" With All Weapons that are Capable of Gibbing
Complete E1L2 100%
Complete E1L1 100%
Activate the Original Soundtrack
Finish the Game in 4 Hours or Less
Complete Episode 4
Beat El Oscuro in 3 Minutes
Get the Bad Ending
Complete Episode 3
Beat NME in 5 Minutes
Eat 3 Porridge Bowls in 5 Seconds
Kill 666 Enemies with the MP40
Run the Game on Maximum Ludicrous Settings
Kill 666 Enemies with Pistols
Beat Krist in 3 Minutes
Complete Episode 2
Kill an Enforcer with a Single Pistol
Get 2000000 Points in One Level
Find Scott's Mystical Head
Kill 3 Enemies at Once with the Barkblast
Beat General Darian in 3 Minutes
Complete Episode 1
Disable Gore
Kill 5 People at Once with Explosives or Magical Weapons
Get Shrooms Mode for the First Time
Kill an Enemy During a Rocket Jump
Gib 50 Enemies
Kill 3 Different Types of Triads with One Attack
Submit a Score to the Leaderboard
Collect 10 Coins in 5 Seconds
Kill an Enemy with an Exploding Barrel
Get Killed by an Enemy Who Was Previously Begging for His Life
Kill an Enemy While Under the Effects of a Jump Pad
Kill an Enemy While He's Begging for His Life
Complete E2L2 100%
Complete E2L3 100%
Complete E2L4 100%
Complete E2L5 100%
Complete Episode 2 100%
Complete E3L1 100%
Complete E3L2 100%
Complete E3L3 100%
Complete E3L4 100%
Complete E3L5 100%
Complete Episode 3 100%
Complete E4L1 100%
Complete E4L2 100%
Complete E4L3 100%
Complete E4L4 100%
Complete E4L5 100%
Complete Episode 4 100%
Beat the Game on Hard Difficulty
Beat the Game on Ludicrous difficulty
Kill 666 Enemies with Knives
Kill 666 Enemies with the Doomstick
Kill 50 Enemies by Using Their Own Traps Against Them
Eat 4 Health Pickups While in Shrooms Mode
Kill 666 Enemies with the Excalibat
Kill 666 Enemies with the Rocket Launcher
Kill 666 Enemies with the Heat Seeker
Kill 666 Enemies with the Split Missile
Kill 666 Enemies with the Drunk Missile
Kill 666 Enemies with the Dark Staff
Kill 666 Enemies with the Firebomb
Kill 666 Enemies with the Flamewall
Kill 666 Enemies While in Dog Mode
Kill 666 Enemies While in God Mode
Play Through All The Secret Levels
Find the Dopefish