If you've held off or ignored free to play shooter Tribes: Ascend, now's a good a time as any. The game recently received an update making weapon upgrades actually viable to acquire by simply playing, and now it's on Steam, with a discount, no less.
Tribes is free to play, sure, but of course there are microtransactions. In this case, you can go a little bigger and splurge on the Starter Pack, now $10 instead of the usual $20. For that you get a lifetime 50% XP boost, four weapons for each base class, two classes (each with four weapons), four perks, and 800 Gs. The offer ends Wednesday, July 4.
Note unfortunately the Steam version of the game requires you to use the external updater for updates as opposed to Steam itself.