Qwirkle is a game of creating lines of like colours or shapes but not both.
Each player gets six small tiles with a coloured shape on it: One of a combination of six shapes and six colours. On every turn, the players will seek out the best placement for as many of their tiles as possible to connect to the tiles in play in order to earn points, but with the caveats that you can only add or create one line, and that you can’t have more than one of the same coloured shape in any resulting connected line. You can have a line of the same shape where each colour is different, and you can have a line of the same colour where each shape is different. Your placed tiles can work in more than one line at the same time as a result of your placement, but everything still needs to work together within the colour/shape line limitations.
Points are scored for every tile you played that makes or continues an allowable line–as suggested above, careful placement can add to other existing lines in order to get additional points from playing those same tiles–and you get a point bonus if you’re able to finish a full set of six shapes or colours.
Tiles you’ve played are replaced from the bag of tiles after each turn.
Qwirkle is fun but at times maddening, such as when you find you can’t get the points you’d thought you’d have at first glance because one or more of the tile(s) you’re placing won’t work with others you’re connecting to that you hadn’t noticed before.
The game ends after the refill tiles are gone and when one player has played their last piece (and gets another point bonus for that).
It’s a fun game, though be warned it can sometimes go quickly and other times seems to roll on for a while. One option you may want to consider, particularly if you’re playing with younger kids, is to put a score limit on it–the winner is the first player to 50, or whatever–rather than the “use every tile available” game ender in order to cut down on how long it can get.