Here is the full list of all 13 Comet 64 achievements.
Solve all puzzles in Disk 1
Solve 'Must Come Down' in exactly 3 lines and 303 cycles
Solve your first puzzle.
Solve all puzzles in Disk 2
Solve all puzzles in Disk 3
Solve all puzzles in Disk 4
Solve all puzzles in Disk A
Solve all puzzles in Disk B
Enter the correct password to access voodoo.txt
Get the secret star
Get every star in the game
Play the secret ending
Play the real ending