I've been awake for over 24 hours developing at the Beta Breakers Gamejam. Here's my entry:
It's a multiplayer game where many players can join simultaneously. New characters are made available to all players at the same interval. Drag and drop a character from the inventory at the bottom of the screen to the board to place it. Pieces need to be placed next to other pieces. Each piece has an attack and health. You start off with a King, and if he dies the game is over.
The minimap is something I haven't built into a game before. It was surprisingly simple to do and adds a lot of convenience to gamers. Ideally it would highlight the viewport and allow for quick navigation (like any other strategy game mini map) but I didn't have enough time.