Well, exid, my second-best-game-ever! is Core Worlds.
Start with a deck of basic units. Draft bigger units into your deck, deploy those units into your attack force, and use that attack force to conquer increasingly valuable planets as the game goes on.
Works very well with two players. Takes about 30 minutes per player. Has deck building/culling and strategic choices ('do I use my energy to draft that card that will be useful later, or to deploy this unit from my hand and take that nice planet over there?'), with a little luck in what cards get drawn onto the tableau.
It is not a patch on Arena or Domination, but a pretty darned good second game.