Here is the full list of all 24 HEPH achievements.
Collect 100 items
Use Tool craft station for the first time.
Craft First key card to unlock to first room.
Finished HEPH on Easy difficulty
Finished HEPH on Hard difficulty
Finished HEPH on Hell difficulty
Collect 1,000 items
Collect 10,000 items
Craft all weapon type
Use Alchemy station for the first time.
Use Weapon station for the first time.
Use Armor station for the first time.
Use Isolator for the first time.
Game over for the first time.
Game over for 99 times.
Craft an Armor
Craft all Armor type
Fully upgrade 1 weapon.
Kill first elite enemy.
Found Ancient One Idol
Kill your first enemy.
Kill 10 Enemies
Kill 100 Enemies
Kill 1000 Enemies