I would recommend using _KEYHIT or _KEYDOWN over INKEY$ and changing that SELECT CASE into IF THENs.
@FellippeHeitor Doesn't CONST have issues when using variables as assignments?
Wasn't there something not that long ago about using a variable to assign constant?
something like:
A%=15-3
CONST VALUE = A%
I can't quite remember now. not having any luck with the search either, but I could swear we've had something like this before.