This game uses the FS3 Skills System by Faraday. It's a dice-pool system rolling d8s.
+roll <skill>+<attr>[+/-mod] to make a simple ability roll.
+roll <charA>=<skill>+<attr>[+/-mod] vs <charB>=<skill>+<attr>[+/-mod] to make an opposed roll.
Attribute and skill may be a name or a number to reflect a NPC's rating.
Mod is optional, to apply a + or - modifier to the roll.
Most of the time you can just roll the skill without needing the <+attr> part; action skills have their ruling attributes pre-set for you, and you should have set the ruling attributes of your other skills in the course of character generation.
In the course of play you will accumulate Luck points. +luck/spend <points>=<reason>
Before your own roll, spend a point to receive a +5 modifier.
Before someone else's roll (friend or enemy), spend a point to apply a +5 or -5 modifier to their roll.
After your own roll, spend a point to get a re-roll and choose the better of the two rolls.
Spend a point to cancel a luck point used against you (for example: if someone gave you a modifier you can spend a luck point to avoid it).
Spend a luck point before your own roll to do something cool. If you succeed, you can do something that is at the top end of what ought to be possible for your character, well. If your roll succeeds, it's spectacular. But you cannot spend luck to be cool if what you're trying to do is not very cool — eg. jumping your horse over a fence when you can barely ride won't cut it, this is a jumping your horse over a flaming lightning-struck tree while you can barely ride but are in hot pursuit of the dark knight sort of thing.
Only one Luck Point can apply to a given roll, so you can't give yourself a bonus and someone else a penalty in the same Opposed Roll. Also, you cant have multiple people all spending luck to help someone.
Additional rules for combats and jousting can be found on the Tournaments page.