Iron Kingdoms
well id rather not take on someone who doesnt know the rules, as it slows the game down to a crawl. believe me, I've done it a few times.
but i can run you down the basics here if you want.
bones of the system:
2d6+whatever
you have several ability scores and skills, to perform an action, you take the ability score plus the skill and then roll 2d6. attack with pistol? Poise+Pistol+2d6. Craft some alchemy? Int+Alchemy+2d6. etc etc etc.
there are ways to get more or less dice to your rolls, usually called either BOOST die, or ADDITIONAL die. there is a difference between the two. you can only have one extra BOOST die, but can have multiple ADDITIONAL dies, though having such things stack is extremely rare.