I'm trying to keep one LED in the pair on and the other off, but at the moment it only works while the button is pressed
A Boolean array which is 9 deep and 2-dimensional (Red/Green) would seem to be the approach that I would use.
Array representation of tic-tac-toe:
Board representation by element:
0 1 2
3 4 5
6 7 8
LED representation
[0, 0] == Red
[0, 1] == Greeen
But you could do this in many, many different ways.
I've been working on my grad project
Surely you know by now how to use arrays?
Ray