That's a great mechanic! I tried to simplify this system for people who had never played before, both for ease of learning and ease of running the game. I left a lot of possible mechanics out chasing that 1page status. There's a lot of room to expand this base system into a pamphlet sized ruleset, but I'll leave that work to others right now.
My next work is more elaborate, more along the lines of a dice pool system with attributes / skills. It does have a "help" mechanic that works a lot like this one (or the one from the 2d20 rulesets), where one player can give their extra successes to another player. Definitely won't be a 1 page system.
I have seen the name RISUS before, but I have zero familiarity with it. I downloaded your RISA PDF - haven't had time to fully read it but so far it seems solid. Seems more on the narrative side, which I like.
Have you played Grok?! at all? I really like it mechanically, but one of the things I kept seeing with new players was difficulty remembering which dice had the number of sides they needed. So I simplified that. Then I took some inspiration from the old White Wolf dice pool mechanics, and probably a dozen other things I've seen over the years.