Carcassonne is a popular casual Eurogame that many gamers use to introduce modern designer games. Carcassonne's strength is the simple yet engaging rules. On your turn you draw one and play one tile, optionally you can place your "meeple," a follower token for scoring. The decisions are simple since one edge of the tile must match the edge of a previously played tile to create a consistent landscape. However some gamers prefer something more meaty and can add any of a number of expansions to add more depth. Expansions range from intriguing to ridiculous such as the, Carcassonne: Catapult -- you fling tokens with a chopstick sized, wooden catapult. However adding expansion breaks the core simplicity by adding more fiddliness.
Caracassone: The Castle is a reworking, a sequel to the original Carcassonne by Reiner Knizia and with Klaus-Jürgen Wrede, the original Carcassonne designer. Although the core gameplay remains the same -- draw-one, play-one -- Caracassone: The Castle is a much deeper game. The theme is also the same, you run a medieval temp agency, sending workers to short-term contract jobs. Key differences are: no edge matching, two-player only, static boundaries, and complex scoring. The game is set up by building outer walls that create an outline of the the castle. The walls do three things: create a defined tableau, offer seven start spaces that tiles can be placed next to, and serve as a scoring track numbered 0-99.
You can play a tile next to a previously played tile or next to one of the seven start spaces. Often several "islands" will form around the start spaces, giving you numerous options for tile placement. Since it's a two-player only game, you can often build large buildings that span multiple tiles without being harassed by three other players.
However the most clever concept of Caracassone: The Castle is the wall (power-up) tiles. The scoring track is a racing mini-game. The number of spaces your meeple moves in the mini-game is based on points you score from the main game. On all thirteen corners, there is one randomized face-down wall tile. These thirteen tiles are drawn from eighteen, and not all tiles are used, to prevent "card counting." The tiles offer score multipliers, extra turns, and other advantageous exceptions. In essence the wall tiles create secret asymmetry of desire, making the game more tense as players behave unpredictably. Since you must land exactly on one of the two spaces that make up the corner to pick up a wall tile, you must plan your scoring in the main game appropriately.
In the early part of the scoring track, spaces 11-44, there many twists that create seven corners. If you want to collect wall tiles in those seven corners, then you must build lots of small buildings or short roads to score small sums. Scoring little by little allows you to navigate and land exactly on corners. Sometimes you will even score a few points for your opponent to make her overshoot corners. Thus you build both big and small buildings to adjust progress on the scoring track. Balancing short-term and long-term gains is what makes Caracassone: The Castle the best of the Carcassonne franchise.
You can play Caracassone: The Castle online via Your-Turn-My-Turn. They offer browser-based asynchronous play that works with most browsers including Safari on the iPad. There is no AI, so bring a friend and introduce him to the best version of Carcassonne.