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