Here is the full list of all 15 The Jewel of Monostructure achievements.
...
Refuse the meeting
Go to a meeting with your friends
Talk to the Shadow
Catch a thief red-handed
Chase the thief
Survive
Act as bait
Open an old wound
Make a deal with the enemy
Make a promise to Anga
Wait for the Brothers to arrive
Kill the monster
Achieve all endings
Descend into the Monostructure