Here is the full list of all 30 Dread Templar achievements.
Kill 100 enemies with throwing katana
Defeat Beelsebur II
Kill 4 enemies during bullet time
Bring the lady her husband’s ring. Solve the super secret puzzle in E5M1.
Defeat Annorbysis
Return the book back to the bookshelf and don't let it get burned by the lava. Solve the super secret puzzle in E4M6.
Dodge all rolling things. Complete the mission of the side area in E4M6.
Find something under the Lava. Solve the super secret puzzle in E4M5.
Don't be afraid, trust your gut feeling. Jump forward! Solve the super secret puzzle in E4M3.
Complete a level and discover all its normal secrets. You must unlock this achievement in levels with at least one secret.
Defend the outpost from swarming of the firebugs. Complete the mission of the side area in E4M2.
Defeat the Curator
Kill the Hell Knight
Find and pick up a pair of bloody eyeballs.
Kill the Spider
Discover a super secret.
Kill an enemy with throwing katana
Kill 8 enemies during bullet time
Two blueprints? Solve the super secret puzzle in E1M3.
Get your running shoes ready. Solve the super secret puzzle in E1M4.
If you know, then you know. Solve the super secret puzzle in E2M1
Obtain the moon key and find out what it can unlock. Solve the super secret puzzle in E3M1.
Find out the ghost captain’s secret. Solve the super secret puzzle in E3M2.
Fulfill the last wish of the little girl. Solve the super secret puzzle in E3M3.
Re-supply water to the Desertville. Solve the super secret puzzle in E4M1.
Complete the game on HELL difficulty.
Complete the game on Nightmare difficulty.
Survive 10 rounds of Guardian Mode on HELL difficulty.
Survive 10 rounds of Guardian Mode on Nightmare difficulty.
Complete a standard level (those without a boss fight)without killing any of the demons