Thanks Adversary!
I haven't think about a rules system yet... For once, it's not intended to illustrate a homemade rpg.

Right now, I would probably use a system resulting of a mix between Qin and Metal systems. Something using 2 ten sided dice (with a zero value for the 0), the lowest substracted to the highest score + attribute ; and a base difficulty determined by the character condition (fatigue, wounds, mental health, etc.) with variations due to skills and special conditions.
But, well, I like to adapt a system to a setting, so... I really don't know for this one since I haven't thought the setting that much.