What is the player called who has a turn?
"You're up!" and "Your turn" are idioms for game players telling a player that it is their turn. For a variable, how about "Active player"?
I have faced the same challenge naming variables in card games, though in my case the word "active" rarely caused any ambiguity. May I suggest one of the following alternatives?
- Current Player
- Focused Player (i.e. the player who has focus, like an input control)