Any expansion to Cosmic Encounter is worth it just by the sheer amount of new alien races you get. Additionally, we always play with the rewards deck and the option to add another player is sometimes very useful.
Must have expansion. The 20 new races will spice up gameplay, and the new rewards deck tosses in some crazy game-swinging effects that will have folks clamoring to join the defense just to earn them. All this and a sixth player, for a great price? Yes, please!
This expansion is certainly worth purchasing, for any lover of the base game. The new races are intriguing, sometimes infuriating, and often game changers, and the new rewards deck is a very welcome incentive to defensive players. Highly recommended.