All Tangled Up
Entanglement is played on a board made up of hexagonal tiles. You start from the red point in the center: it marks the beginning of a path that you create as the game proceeds. Your goal is to create the longest path, twisting and turning around the board, while trying to avoid dead ends at the edges of the board as well as the center tile. The longer the path you create, the more points you receive.
Each tile has different lines, which let you make new connections and extend the path. You rotate a tile using either arrow keys or a scroll wheel. Once you've decided where the path is going to go next, click on the screen to add a new tile. Making a path wind back through tiles you've already played earns bonus points. While the game mechanics are basic, to be successful you need to have chess-like foresight, rotating tiles in anticipation of future connections and trying to minimize potential dead ends.
But what really makes Entanglement rise above other online games is the obvious care put into every detail. The board looks as if it's created from hand-polished wood, the tiles spin quickly and smoothly, and the controls are easy to use and intuitive. One possible improvement is to have a clock that you play against -- this would make your decisions snappier. And then you might be able to extricate yourself sooner from an all-too-addictive experience.