Mahjong games come in two varieties: The "Shovelware" type, which contain thousands of boards, tile sets, and so on, and the "Enhanced Gameplay" type, which focus on graphics, animation, sound, and innovations. In-Poculis Mahjong ($14, shareware) is the latter type.
The core rules are the same as ever: Match tiles to remove them from the board, until you either remove them all or you can't remove any more. Gameplay is fun and fast, with animations and sounds that are not overly intrusive. There is a unique scoring mechanism which rewards combos, such as removing all four of a given tile at once; this is another feature that is new to me.
Not to be outdone by shovelware, In-Poculis includes a large selection of both layout and tiles. It presents these to you in sequence; in order to play layout two for a given tile set, you must first play layout one. The layout and tile sets are linked, something I had not seen before: Each set of tiles has its own set of thematic layouts. One tile/layout set--Christmas-themed, for all you early shoppers--must be "unlocked" first.
I have some quibbles, though. First, the English translation, while understandable, is slightly fractured. Second, the game automatically reshuffles the tiles when you reach the point where you can't remove any more. This cannot be turned off; indeed, the game has no "Options" or "Preferences" dialog at all, nor any kind of standard Windows menu bar.
On the plus side, unlike most games of this genre, In-Poculis Mahjong offers a completely unlocked trial. It is a true shareware game, where you are expected to be "on your honor" and register if you enjoy and play the game.
A warning: If you click the Register button on the In-Poculis site, the site it takes you to flashed up many alerts under Norton. When I investigated, I found the issue was that the site which In-Poculis uses for registration also serves, on other pages, to register assorted programs such as keyloggers which are rightfully viewed as suspicious. The actual registration page for In-Poculis did not appear to be harmful in any way.