Star Realms: Colony Wars

Colony Wars is faster, and probably better balanced than the original game. But combining all three base sets is my favorite way to play. Colony Wars helps boost the power of cheaper cards and dilute the power of expensive cards a bit, and when all three are combined, you get a very rewarding set of decisions with a ton of replay and variability that is fairly balanced between the sets

A lot of the problems I have with most deck building games is it can often feel like playing solitaire where other players watch you take your turn until one of you wins, or the random chance of getting cards and the high financial buy in price of some TCG's like Magic the Gathering (which while still the best one, still has a huge financial investment problem). Star Realms doesn't have these problems as you are all competing for and from the same pool of resources to expand your deck which you'll use to deplete your opponents' health, and the expansion boosters are always the same cards and are tools to boost different gameplay styles. This is a good 2 player game and a better 4 player game, but it doesn't reach its full potential without at least a few of the expansion packs.

If you're new to Star Realms and don't intend to play 4 player games, stick to Colony Wars as your starter pack, and if you need more grab the following boosters:
United - Command
United - Assault
Crisis - Bases & Battleships
Crisis - Fleets & Fortresses

The following, while also good, are an acquired taste and subject to the playstyles of the table:
United - Heroes
United - Missions

And if you're finding the gameplay still a bit stale and lacking in randomness, give the Cosmic Gambit Set a shot, though you may want to house rule some cards out/when you can play them as they can be extremely powerful.

When the base game is feeling a little tired, this is the expansion to buy. While it can also be played stand alone, it works even better mixed with the original cards. More bases in this set changes the dynamic of the game without adding any additional complexity. Not essential, but a great addition for the price.