Well, it’s kind of a base building game, in that you can build your own starbase. The idea is that you’re independent, and can run missions for the Federation, as well as the Klingon and Romulan empires. You build ships and improve them with stuff you get from fighting and mining. At a certain point you become eligible for PvP which I don’t really engage in because, since I don’t pay any money into the game, I’m relatively underpowered. My base gets raided every so often by much more powerful players, but I take it as a cost of living.
I’m not doing a good job of explaining why I like the game, but I do find it quite addictive. I’ve joined an alliance of other players so we can kind of engage in “collective bargaining”, aka defend each other if someone decides to attack one of us, kind of like NATO. Naturally, as you level up you get access to more powerful ships and can enlarge your starbase, which I find fun. But basically it’s kind of a time waster, I guess.