Here is the full list of all 21 NeverEnd achievements.
Buy a Bow and a Rod in one run
Finish the second quest
Kill your first mini boss
Walk into a room with 6 Zomborgs
Find one elemental sword
Finish the first quest
Buy your first item
Die in the first 10 seconds
First death
Kill your first enemy
Buy all items
Kill every mini boss in one run
Collect all hats
Konami code
Beat the game
Complete the game with the stick
Kill the dummy
Walk through 100 rooms in one run
Kill 50 enemies with the bow
Get 20c in one run without the Rod
Kill the final Boss