(Pardon the terrible title. If you can think of a better one, feel free to edit.)
Technically, game theory consists of games and strategies. However, from the tag wikis, it looks like they are all the same.
The tag wikis:
The game-theory tag: Puzzles that involve strategic decision making, usually involving either competitive or cooperative choices between a number of participants.
The game tag: A puzzle that asks for determining the winner in a (typically combinatorial) multi-player game.... The solution to a combinatorial two-player game puzzle usually consists of a full analysis of all game situations, by classifying them into "wins" and "losses" for either player.
The strategy tag: A puzzle whose solution is a methodological plan of action for realizing a specific goal as effectively as possible. The solution, rather than being an object or word or single action, specifies how to act in a multi-step interaction, basing each action off of previous actions not under your control.
All of them says, "There's a game. Find out if there is a strategy such that you/someone will win. If there is, find it." We shouldn't have three tags for basically the same thing.
There are several options: