I don’t have any experience with RuneQuest, upon which, I believe, Mythras is based. However, I had seen a post on Reddit in which someone commented on liking a combat mechanic from Mythras. Originally, I was just going to surgically remove that tidbit but then I thought, what the heck, let’s look at the whole thing.
This is the free, pared down version of the ruleset. From DriveThruRPG:
"Mythras Imperative is a 38 page introduction to the Mythras system, designed for both newcomers and old hands. It gives you a pared-down, simplified version of Mythras but still with enough options and depth to be a playable game. The rules cover character creation, skills, the core mechanics of the game, spot rules for different circumstances, combat mechanics, and several creatures from fantasy, real life and science fiction.
"Is this a fantasy game?
"We’ve made Mythras Imperative generic. Skills cover the ancient, modern and futuristic settings, and the weapons include firearms. So Mythras Imperative gives you the starting point for adventuring in any time period you want. Other supplements, and the core Mythras rules themselves, expand on things like magic, vehicles, psionic powers and so on.
"What else can I do with it?
Mythras Imperative can be used by third party publishers to develop their own, Mythras-powered games, in conjunction with the Mythras Gateway License. This simple agreement extends our permission for the Imperative rules to be used wholesale in new systems people want to create. Contact us for more details."