Considering the limited nature of the game, we could add a 3rd longer category for beating the game 8 times and unlocking the hidden achievement.

Yeah that's a possibility (I didn't even know of the existence of this hidden achievement lol)

I would also like to put forward a suggestion. A category where you have to get all the numbers and complete the whole run checkpointless to get the full clock animation and the "secret" boss, maybe call it something like Full clock% or True 100%.