This isn't a puzzle in any traditional sense, however I thought I'd share it here anyway:

Noughts and crosses (tic tac toe) is famously a game which will always end in a draw if both players are playing rationally.

However with a simple change to the rules which would appear to be both sensible and fair - namely that neither player may place their first mark in the centre square - the player who goes first can always force a win.

The puzzle then, if there is one, is merely for the reader to satisfy them self that this is true, and to determine, if you were going first, how you would force a win.