Stealing the Diamond achievements

Stealing the Diamond has 11 achievements in the legacy version, and 10 achievements in the remastered version.

All versions
These achievements are available in both versions of the game, but some names may have been changed from the original.

Intruder on a Scooter / Aggressive
Win the game through the Intruder on a Scooter/Aggressive ending. (Bust In → Ram → Shield → Tow Cable → Rock → Bubble → Diamond = Intruder on a Scooter/Aggressive)

Unseen Burglar / Undetected
Win the game through the Unseen Burglar/Undetected ending. (Sneak In → Teleporter → Penny → Wire → Hammer → Plank → Diamond = Unseen Burglar/Undetected)

Just Plain Epic / EPIC
Win the game through the Just Plain Epic/EPIC ending. (Sneak In → Pick → Plane → Left Arrow → Mushroom → Bottom Left Button = Just Plain Epic/EPIC)

Fail Champion / Failsterpiece
Get all 40 unique fails.

Like a D6
Lose 6 points. This can be done by using the Jumble Hoppers 3 times, since the player is deducted 2 points for each fail.

tl;dr / Secret Medal
In the fail screen for the Wormhole Rifle/Portal Gun (Portal Gun in the original version), read the long description and click on the word "here".

BUNP
In the final choice screen for Unseen Burglar/Undetected, choose the Snap Neck option, which will cause Henry to fall off the stairs. It's a reference to the webcomic Sweet Bro and Hella Jeff, a parody comic by the same author as Homestuck.

100111010/01100010
During the Fail screen for the Goodball (Pokéball), close at least 3 error windows.

Original version only
These achievements are only in the original/legacy version of the game.

Failtastic
Fail a total of 55 times. Since the game only has 40 unique fails, this required the player to get some fails more than once on purpose.

sPell mAn / It's a joke guys
Click the misspelled word on the Liquidificator's instruction sheet. Ironically, it is the word "misspelled" that is misspelled ("Mispeled").

Obscure Medal
Click on every portrait you can find in the museum (Zeus-Rage, LOL wut pear, Angry Hitler, Pyramids, No U Luigi, munas 561 A.D., Leonidas IV 672 A.D.)

Remastered version only
These achievements are only available in the remastered version.

The Ledger
Find all 27 bios.

Connoisseur
An updated version of the Obscure Medal from the original game; steal all the paintings in the museum.

The player can find all these paintings and collect them in the following:

WWII Exhibit
Number of paintings: 7

Retro Exhibit
Number of paintings: 3

Grand Exhibit
Number of paintings: 6

Lobby (IoaS)
Number of paintings: 7

Medieval Hall
Number of paintings: 3

Hallback
Number of paintings: 4