Abalone is a two-player strategy board game which can be quaintly summarized as "sumo wrestling with marbles," as the objective is to push the opponent's marbles off the edge of the board. The rules are quite easy and can be mastered in a minute or two, and the flow of the game is generally fast-paced.
The prefix "ab" means "never." The premise of this game is that you're never alone when playing.