Yes! You can challenge others to any competitive game:
Board games (Chess, Backgammon, Checkers, Othello)
Card games (Poker, Magic: The Gathering, Yu-Gi-Oh)
Sports (Basketball, Football, Tennis, Table Tennis)
Strategy games (Risk, Stratego, Battleship)
Take a photo of the final result as proof!
Must be competitive: One player wins, one loses - no ties or cooperative games!