Here is the full list of all 11 Floppy Heroes achievements.
Complete the tutorial.
Complete level 5 in Singleplayer Mode.
Complete all 10 levels in Singleplayer Mode.
Complete Singleplayer Mode without equipping a helmet.
Unlock all pieces of head armor.
Unlock all pieces of torso armor.
Unlock all pieces of arm armor.
Unlock all pieces of leg armor.
Unlock all one-handed weapons.
Unlock all two-handed weapons.
Upgrade a piece of equipment.