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