The interrupt thread gave me ideas for loose initiative with more complex layers kicking in only when needed. Quick draw scenarios becoming a sort of mini game of its own. It's a bid system (dice pool, for example).
Act : turn your card and state your action
Challenge initiative : Turn your card and put it on top of the previous one. If it's a draw or close enough, put your cards side to side. You're now "competitors". There's no limit to the number of competitors.
Start the challenge
Make your starting bid
You write your intended action on a note and hide it (eg : turn it face down)
Eye of the cyclone
If all competitors agree to it they can now change their starting bid or intent
Else, competitors can fold, see or raise
Until all the competitors who didn't fold agree to see
Then, everybody reveals intents
Highest bids have precedence
(still a draw ? look at the card stack, first player goes first as in FIFO)
(still a draw ? youngest go first)
If an intent can longer apply, you just lost your action (but maybe the other player will let you get away with a consolation action ?)
When all cards have been turned, end of turn.
For non-standard actions, keep resolution time scale in mind.
Foreseeable problems in the implementation ? in the principle ?