Lancelot

In this abstract strategy game, players take turns placing a single piece of their own color on the board. When you have N+2 pieces than the number of pieces of other players in that row or column, you take them as prisoners.

This systems is some what similar of the more recent Kahuna, as "chain reactions" are quite the same. The game is totally abstract, but it works fine with any number of players (2-5). A crazier advanced mode allows players to consider even diagonals!