What more do you think is a better option after running through many possibilities in your head?

Ainsi, After

24 hours, I’m finally on level 255 of Pacman.

I believe you also use “on” in the other video game variations as well ( server, map, chapter…). but I’m open to hearing other possibilities.

As pointed out by @painfulenglish, ” at ” seems to be a safe substitute as well.