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