Here is the full list of all 12 BloodRayne Betrayal achievements.
Find the hidden idol
Activate BloodRayne: Betrayal's alternate soundtrack
Complete the game
Chain-explode 5 enemies
Kill 5 enemies with a single gunshot
Collect all the ancient vampire skulls
Finish every level with the ranking "Dhampir"
Hop on 50 heads in a row without touching the ground
Complete any level while taking no damage
Kick open the Coffin Rocket 20 times
Defeat Crab Puncher without getting hit
Kill 250 enemies with environmental hazards