A little video to explain...So, basically, Tribes: Ascend is a First-Person-Shooter (no, wait, come back!) that banks on the skiing system.
You see, you can turn off friction in that game.
Jet-pack up slopes and ski down hills, and soon you're going fast. Really fast. I've played it, and it's very good. As for the "Free-to-play", everything is unlockable for free, but you can pay to unlock classes. You can also test the classes (without bots) in the free-roam.
Right now, it's in closed beta, but I have four codes. Does anybody want them?