http://www.berserk-games.com/ts/A physics sandbox with boards, cards, dice, rpg miniatures, and game pieces. Instead of forcing rules, the game let's you and whoever else is playing deal with that. Also, you can flip the table.
Constantly being updated with new features and has integrated Steam Workshop for creating games.
There is a download link for a demo, which is single player. Try it out, but the real fun is playing with friends.
Let's start with this, what games would you like to play?