Here is the full list of all 35 Thomas Was Alone achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Find the second achievement pickup in 'Y+1, X+1'.
Finish the game.
Find the first achievement pickup in 'Y+1, X+1'.
Begin 'Y+1, X+1'.
Find the second achievement pickup in 'Generation'.
Find the first achievement pickup in 'Generation'.
Begin 'Generation'.
Find the second achievement pickup in 'Design'.
Find the first achievement pickup in 'Design'.
Begin 'Design'.
Find the second achievement pickup in 'Itterate'.
Find the first achievement pickup in 'Itterate'.
Begin 'Itterate'.
Find the second achievement pickup in 'Invert'.
Find the first achievement pickup in 'Invert'.
Begin 'Invert'.
Die 100 times.
Find the second achievement pickup in 'Purge'.
Find the first achievement pickup in 'Purge'.
Jump 2400 times.
Find the first achievement pickup in 'Origin'.
Jump 1600 times.
Begin 'Purge'.
Find the second achievement pickup in 'Associations'.
Bounce on Laura 100 times.
Find the first achievement pickup in 'Associations'.
Begin 'Associations'.
Find the second achievement pickup in 'Origin'.
Jump 800 times.
Begin 'Origin'.
Find the second achievement pickup in 'Array'.
Find the first achievement pickup in 'Array'.
Begin 'Array'.
Find the second achievement pickup in 'Spawn'.
Find the first achievement pickup in 'Spawn'.