Elite: Dangerous has a surprisingly fun "mini-game" with it's competitive CQC game mode. Compete in a fast-paced fight to the death against other skilled fighter pilots in some startlingly tight spaces. Frontier Developments is now offering just that module as a separate standalone purchase for those wanting a different kind of competitive experience.
For $7.49, you can take to the arena in Elite: Dangerous and compete against your peers in what they're calling the ultimate futuristic gladiatorial contest. Purchasing from the Frontier Store will get you a discount on the upgrade to the actual full game, minus the full purchase price of ED: Arena. It doesn't look like Steam offers such a deal at the moment.
CQC mode in Elite: Dangerous has the potential to be a new type of eSport, leveraging a different skill set than the usual FPS games require by having you also think about how to maneuver a ship with true, realistic Newtonian physics. You can either have automatic compensation of inertia to drive you in the direction your nose is pointed, or turn off all the assist and pull off maneuvers that aren't possible in gravity.