Here is the full list of all 22 Alien Splatter Redux achievements.
Score over 500000 points
Complete the Boss Rush Mode
Complete the Glitch Worlds
Complete Extra Stage
Score over 250000 points
Complete Stage 7 without dying
Complete Stage 7
Complete Extra Stage without dying
Complete Stage 6 without dying
Complete Stage 5 without dying
Complete Stage 6
Complete Stage 5
Score over 100000 points
Complete Stage 4
Complete Stage 4 without dying
Score over 50000 points
Complete Stage 3
Complete Stage 3 without dying
Complete Stage 2
Complete Stage 2 without dying
Complete Stage 1 without dying
Complete Stage 1