A family of (abstract) games based on specific game mechanics designed by Martijn Althuizen.
All the games in the Tixel family have pieces that 'protrude' into adjacent board spaces during play. In the oldest games of the family this is a result of the shapes of the pieces. In the more recent games the protruding is a result of both the shapes of the pieces, as well as of how pieces are oriented in relation to the spaces of the board.
The oldest (published) game in the family, Tix, is from 2007. The initial idea for the 'protrusion concept' however, dates back to 2004.
After Tix came Tixel, which combines the 'protrusion by orientation' mechanic with pieces whose shapes 'contract into' the board spaces they occupy.
Following up Tixel is the game Regatta, which introduces pieces that each also have a single rounded corner (besides a 'concave edge').
A secondary key game mechanic is the chaining of moves; sacrifice a piece and you get a bonus move in which you have more options than in regular moves. Not all games in the Tixel family apply this game mechanic, but most of them do.