Puzzle Strike 3rd Edition and the Shadows expansion both have totally different multiplayer modes than the 2nd Edition. There's a free-for-all mode with no player elimination now, and also a 2v2 Team battle mode. Several chips were reworded in the 3rd Edition base set to accomodate these modes. Also, there Combine chip is different now, with a -$1 on it (long story why, but it's a good change!) and several chips have been rebalanced in response to that. Also, several puzzle chips in the base set have been powered up in the 3rd edition to be more useful. For example, the chip "Secret Move" was hardly used in the 2nd Edition, but is now pretty spiffy in the 3rd Edition.