Here is the full list of all 16 8-Bit Commando achievements.
Complete every mission on hard difficulty
Complete at least one versus match
Collect every type of powerup
Complete any mission in coop
Complete a mission without dying or losing any health
Complete the seventh mission
Complete the sixth mission
Complete the fifth mission
Complete any mission in under 2 minutes
Complete the fourth mission
Complete the third mission
Complete the second mission
Take out 81 bad guys
Fire over 666 bullets
Complete the first mission