The idea is to develop a game you can run with some paper and pencils and two differently colored d10's, and not much else. How exactly the scenario creation works could vary, but I imagine it'd be something like this:
The GM has two friends over who've never roleplayed before and want to try it. The group comes up with a famous story / setting, and two characters from that story they'd enjoy portraying, that we then put in a new situation. Say, Luke and Leia having an adventure between A New Hope and Empire wherein they have to break some Rebel prisoners out of an Imperial work camp. This part needs to be completely collaborative, with the GM willing to go along with anything that will allow the creation of an immediately compelling, dramatic situation. (It doesn't have to be famous canon characters, that just seems like an easy way to get started with new gamers.)
You don't, initially, write anything down on your sheet other than your character's name and, let's say, three Passions. "Love: my family," (heh) "Ambition: become a Jedi," "Faith: the teachings of Ben Kenobi" or whatever. One is rated at 30%, one at 40%, one at 50%.
Then, when a challenge arises, the GM simply asks, "Based on your concept of the character, what do you think is the percent chance your character will succeed at this?" I don't anticipate people abusing this, especially non-gamers, but there are all kinds of ways you could mitigate any power-gaming tendencies.
My current thinking is that whenever you add an immediately-relevant skill to your sheet, you also add a different skill not applicable to the current scene, at 100 minus the rating you assigned to the new one. So if I give myself "Brawl" at 63%, I immediately need to give myself another skill, say, "Dance," at 37%. The GM's job is then, of course, to introduce a dance competition.
Anyhow, the player adds the new skill to their character sheet at the listed percentage, say "Climbing 70%."
(You obviously have to be careful naming the skills, so they're neither too broad nor too narrow. As a rule of thumb, "Fighting" is too broad, but "Dagger" is too narrow. Any GM running this game needs to have a significant amount of experience and trust in their judgment. Of course, genre is an important consideration for this question of scope as well: if we're doing a martial arts game, maybe we do want training in different weapons to matter.)
Use the usual indie RPG techniques of stake-setting, Let It Ride, scene framing, Roll or Say Yes, etc.
Any time you fail a check, the skill goes up by 1%, and you also gain an Experience Point to be spent later. (Make a box on the blank piece of paper for Experience Points.)
It's also perfectly fine to bring in some more advanced techniques from Mythras proper: if, the next time you use Climb, it's a much steeper slope or they have worse gear or whatever, you could have them roll at 2/3 of their listed skill value. You could introduce crit successes and failures, too, with no problem, as long as you know the basic rules (crit successes are rolls that are 1/10th or less of the skill, so like a 7 or less for a skill in the 70's).
Next: more about Passions.