A try to build a simple D6 RPG system. It is intended to be understandable by a 10 years old child.
Core principle is "roll a certain amount of D6 (attribute), keep the best, add skill level, dices with same number are bonuses. Match the requested difficulty, excess points give the quality of the success".
5: easy 6: normal 8: hard 10: impossible
my character is quite smart with an attribute intelligence of 3, and has a skill 2 in investigation. I roll 3D6 against a difficulty of 6, get [1 1 5]: I keep the 5, add 2 for the skill, and an other 2 for the pair of ones, giving me a result of 9, outstanding success!
A dragon tries to rip a wall, he has 5 in strength and a mass destruction skill of 4. He rolls against a difficulty of 10, and gets [3 3 3 5 5]: he gets 5 (best score) + 4 (skill) + 2 (the pair of 5) + 3 (the three 3) = 14. There is a huge breach in the wall, the undeads are coming!