Caylus is a much-hyped game. The first printing sold out so quickly, people were calling it the second coming of Puerto Rico. Due to this popularity, Big Daddy Creations is releasing a universal iOS port this week. Caylus is a pure Eurogame, putting elegance over a rich theme. Although, you play a master builder constructing a castle in Caylus, France, you spend most of your time changing one color cube for another cube, which in turn will be converted into another color cube.
Caylus popularized the worker-placement mechanic whereby a player places a token (a worker) from a menu of choices, denying others that specific choice. Furthermore, the Provost and Bailiff mechanic is fascinating because they are neutral pieces (white discs) that any player can spend resources to move. You can use it to speed the game up as well shut down other player's buildings, and increase tension around their movement.
Caylus is also available as a Windows fanware by Jason Long.