Here is the full list of all 35 Neon Abyss achievements.
Played the Roulette machine 99 times.
Fished 10 times in fishing room.
Complete a run without picking up any hearts.
Made deals with Smirk Co. 99 times.
Acquire 10 heart containers in a single run.
Jump in the air for 10 times before landing.
Stepped on worms 999 times.
Opened 999 locked chests.
Defeat Goddess of Illusion.
Defeat God of Violence.
Defeat God of Machines without getting hurt.
Jumped 9999 times.
Found 5 secret rooms in a row.
Acquire 10 shields in a single run.
Successfully hatch eggs 5 times in a row.
Get 50 eggs in a single run.
Defeat the God of Electricity.
Defeat God of Machines.
Defeat God of Darknet.
Death is another beginning.
Get killed by your bombs.
Failed to hatch eggs 5 times in a row.
Get killed by environment damage 9 times.
Unlock 6 Characters.
Died in the Abyss 99 times.
Found 99 secret rooms.
Entered the abyss for the 999th times.
Unlock Abyssal difficulty.
Get killed by your own bomb while in the air.
Completes the Piano challenge 10 times.
Defeat Athena in Abyssal Difficulty.
Complete a run without losing any hearts.
Empty 4 shops in a single run.
Defeat Argus without picking up any items.
Dance in the bar for 30 minutes.