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.
Spreadsheet
I just wish it didn't feel like playing a spreadsheet.
Although it is surprisingly well balanced, it does seem to suffer a little from being the person playing the uncontested strategy i.e. there may not be a dominant one - although the favour track is always pretty good - but merely a dominant one in the game you happen to be playing. And I'm not sure you can recognise it until it's too late to matter. Then again, maybe it's just that I haven't worked out how to switch...
Caylus
Caylus is a really strong game; there's a lot of moving parts and creative interactions, and it tends to have at least one interesting decision a round. I like the building mechanics: trying to find a building that supports your strategy uniquely, or that's useful enough to others to get used often (but that doesn't give them too much of a boost when used).
Another feature it has that's sometimes missing in Euros is "nameable strategies". You can lean a few different ways in terms of what resources and points you go after, and considering how these strategies have interacted or might interact gives you something to chew on between games.
The very recent iOS version seems quite good to me; I've only played a couple times, but it seems mechanically sound, looks good, and the AI plays (at very least) well enough to learn the game. The game also proceeds a bit faster when automated, which is a big plus (the mechanics can tend to towards positive feedback cycles, and a longer game can feel like a real drag if you're behind).