Having played it at BGG.CON, I must say Eminent Domain is the first deckbuilding game that I think deserves mention in the same breath as Dominion*. I certainly won't say it's as good, but it's a very worthy game in its own right. It takes elements from Dominion, Race for the Galaxy, and Glory to Rome, and it synthesizes them in a rather clever way that makes for an excellent strategy game. As an added bonus, it has a really simple ruleset, with the only real learning complexity coming from having to read through the level 2 and 3 Tech cards. (The level 1 Techs are just improvements on the basic Role cards' action abilities.)
1) Each turn, you may play a card from your hand (Technology or Role card) as an action.
2) Then you must choose a Role card you will lead, taking from the supply and putting it in front of you. You may boost it with similar cards to increase its effect. When you're done, you (usually) discard all the cards, including the new Role card that it added to your deck. Other players in turn may follow on the role you've led, playing similar cards to execute a weaker version of the role.
3) Then you may discard any remaining hand cards you like, keeping others in hand, and draw up to your hand limit (5 by default).
Roles do things like discovering new planets and adding them to your tableau ("Empire"), amassing ships or colonies to conquer or settle the planets you've discovered, researching new technologies (cards added to your deck or your Empire), and producing & trading goods on your planets. VPs derive from settled/conquered planets, advanced techs acquired, and chips received for traded goods. Many planets give various bonuses like increasing your hand size or automatically boosting the effect of one of the Roles.
In short: You build a tableau which is worth points and can be used to churn more points by goods production and trading (like Race for the Galaxy) via a Role selection and Lead/Follow mechanic (like Glory to Rome) using a hand drawn from a deck you build during the game (like Dominion). The novel mechanic is that choosing a Role adds a copy of that Role card to your deck (whereas researching techs is more akin to Dominion's Buy mechanic). Technologies encourage clever card combinations like you might see in other card-based games. The really unique strategic element I've noticed so far is that Eminent Domain can reward you for building one engine, then tearing it down mid-game and building a new one. As a simple example, in one game I churned a full-bore Colonization engine until I had something like 7 Planets settled, then trashed all my Colonization role cards while rebuilding my deck into a Produce/Trade engine that I churned for VP chips until the end of the game. Alternately, I've seen very successful single-engine strategies, like one where somebody got a crazy combination of techs that allowed them to eventually conquer some 15+ Planets by the end of the game, ignoring Production entirely.
The only thing that worries me after about 6 plays is that it won't seem quite as fresh after 60. Every game uses the same Technology and Role cards, with the only thing really cajoling you to pursue different strategies from game to game being your random draws of Planet cards. OTOH, I suspect once a group of players becomes really experienced with it, there may not be any extra turns to dally around forcing a Tech strategy you like in spite of Planet draws that are pushing you toward doing something else. And of course, in 3p and 4p games (which is where it really shines to begin with), the Lead/Follow mechanic means it's critical to adapt to what your opponents are doing.
*Noting that there are some other superb card-based strategy games like Race that are not deckbuilding games.
