For achievement hunting, it's recommended to back up your save. You can find them in the local folders. (not the game directory)
The two hidden achievements are secrets...
Viewing post in Save Files and Secret Achievements
Ah okay, got it. I'm doing good so far at completing all of the achievements. Here's the list of the ones I still need to complete (Outside of the secrets.)
1 Defeat - 2
You're the Monster - Defeated a friendly enemy. (I have no idea how to do it )
Spectral Buffet - Devour 100 enemies.
2 Item - 1
Master of All - Had every curse and upgrade active at the same time!
3 Milestone - 3
Getting the hang of it - Made it to floor 30
Ascend into madness - Made it to floor 50
No exit in sight - Made it to floor 100
4 Completionist - 7
Heart of Violet - Reach the max health of 300.
Gallery Enthusiast - See every painting.
Wand of Amethyst - Max out the Wand's power.
Ghost Lover - Befriend every enemy that can be befriended.
Ghost Charcuterie - Eat every enemy that can be eaten.
Ultimate Knowledge - Filled out the entirety of the Ghostiary.
Thousandarie - Had $10.000 Gold at once in one run
5 Skill - 1
Bonk - Get hit by a chair 100 times.