Here is the full list of all 11 Isomorph achievements.
Reach the unreachable laser in Level 2-3.
Don't use all of the cubes in Level 4-5.
Open the final door in Level 2-6.
Activate all three pressure plates at the end of 4-1.
Make good use of the platform in Level 3-1.
Get to the end of Level 1-4.
Show your skill in Level 1-6.
Time your movements correctly.
Show a mastery of platforms.
Get to the end of Level 4-3.
Finish the game.