Legions: Overdrive is a "spiritual successor" to Tribes, borrowing gameplay elements from the series such as skiing and jetpacks. It's completely free and supports modding, user-hosted servers and more.
This is a tutorial aimed at previous/current Tribes players who are interested in Legions: Overdrive, though it's also useful for those who haven't played Tribes before.
Tribes: Ascend Config - Pastebin.com