Here is the full list of all 25 Biomech Hell achievements.
Kill 100 enemies with the main weapon.
Kill 30 enemies with the flamethrower.
Kill 10 enemies by head-shot.
Kill 40 enemies by cutting them in two.
Kill 20 enemies by explosions.
Kill 150 mutants.
Destroy 20 robots.
Destroy 5 vehicles.
Collect 200000 points.
Complete the Forest Stage.
Complete the Factory Stage.
Complete the Nuclear Power Station Stage.
Complete the Warehouse Stage.
Complete the Abandoned City Stage.
Complete the Mountains Stage.
Complete the Port Stage.
Complete the Cavern Stage.
Complete the Laboratory Stage.
Complete the Warship Stage.
Complete the Observatory Stage.
Complete the game with the best ending.
Complete the Boss Rush Mode.
Complete the Super Arcade Mode.
Unlock all artworks and visit the Art Gallery.
Don't give up, play again!