Here is another game mechanic for those who dont want to get too technical in their rp.
For every challenge the GM rolls for dificulty: 1d6 - (strengths your character has relevent to the situation) + (conditions that work against you)
Dificulty = number of dice players need to roll to pass the challenge. As long as you dont roll a single 1, you pass. Otherwise you fail at what you are doing, or barely succeed and but take a condition while doing it.
If you manage to reduce Dif. To 0 or less you automatically succeed.
Example: A rat comes to attack you. Gm rolls a 4, subtracts 1 because you are skilled in combat, making Dif. 3. You roll 3 dice. As long as you dont roll a single , you defeat the rat.
You could also run a high stakes game where each 1 rolled subtracts from your health or disposition (what ever you want to call your hp) and that character dies when you run out.
Enemies can have a disposition or hp too, and each success deals damage to them.
And thats the long and short it. Simple easy to use.