Here is the full list of all 50 Merri Puzzle achievements.
Encounter exploding blocks
Reach Check Point 7
Reach Check Point 6
Encounter vanishing blocks
Reach Check Point 5
Use the red square of awesomeness
Reach a room with gravity controls
Reach Check Point 4
Reach a locked room
Encounter lava
Reach Check Point 3
Touch two triangles in puzzle mod
Encounter a peg based level
Use the wobbly triangle
Reach Check Point 2
MORE PITS!
This really is the pits!
Bounce things off of more things!
Encounter a level with two exits
Encounter a level with more than one solution
Check point found
Encounter a pit
Encounter gaps in a level
Make a ball
Encounter green diffuser blocks
Break some breakable blocks
Encounter yellow blocks
Beat easy mode
Beat Hard Mode
Encounter Invisible Walls
Reach Expert Mode
Beat Expert Mode
Multiple Objects in One Room
Use Green Blocks To Break Red Blocks
Reach Check Point 8
Reach Check Point 9
Reach Check Point 10
Reach Check Point 11
Reach Check Point 12
Reach Check Point 13
Reach Check Point 14
Reach Hard Mode Check Point 2
Reach Hard Mode Check Point 3
Reach Expert Mode Check Point 1
Reach Expert Mode Check Point 2
Reach Expert Mode Check Point 3
Reach Expert Mode Check Point 4
Reach Expert Mode Check Point 5
Reach Expert Mode Check Point 6
Reach Hard Mode Check Point 1