Here is the full list of all 32 Inline achievements.
Lose after using 5 skips in a row
Reach streak of 5
Completed 3 lines in 9 moves
Beat your own highscore 3 times
Play Custom Mode
1000 lines cleared
Play 20 normal games
Drop a shape outside of the grid
Skip when no more skips are left
Reach a combo of 4
Rotate a shape that will not change the orientation
Reached more than 9000 score in total
20 skips used
Reach streak of 3
Reach max level 10
50 lines cleared in one session
Reach combo of 3
Reach level 5
Reach level 5 without skips
50 shapes placed
Lose with no lines cleared
Click and hold main menu title for 5 seconds
Spin one shape 20 times
Skip a single block
Reach 600 score in 50 moves
Find every easter egg
Type RAIN at the main menu and let the rain work its magic
Repeatedly press ESC at the main menu to display the game with inversed colors
Use the Gameboy command in the console and enjoy tastelessly emulated graphics from the past
Try to access debug features and meet their guardian
Push an AI to crash the game
Find the option hidden in the options menu, and enjoy them "soft-body physics"