Castle Chaos is a fast paced local multiplayer game for 1 to 4 players. Build castles with tetris-like shapes and shoot cannons to destroy your opponents' castles. Available for PC, Mac and Linux.
One of my favorite games of my childhood was Rampart. Especially the SNES version, as I never had any competition even when I found an opponent as a kid. This game looks to do what I liked about that game, so it has found a place at the top of my Steam wishlist.