My 3eish concept has been through a lot of drafts, but I recently arrived at the following rules for action sequences (combat) and I think they're quite close to what I'll use in the final thing. Who knows, maybe I'll even use the same words.
rule
Encounters take place over rounds, representing a few seconds each.
Actions
Each character may act once per round. Characters act in order from highest initiative (aka adrenaline) to lowest and then from highest Wisdom to lowest. Changes to initiative affect the next round's sequence, not the current round.
A character may make only one reaction between one action and the next. They may only react a second time by forfeiting their next action.
Actions that take a few seconds require a character to commit to them; a committed character can't react until after their next action.
Movement
A character may move up to their Move score as part of their action; if they take no action, they may move twice that amount.
Careful movement---such as balancing or leaping---requires a check; a failed check occupies the character's action. A failure by 5 or more means they fall.
Contested movement---such as climbing, parting tangles or swimming---requires an action, at least one free hand and a check; a failed check takes a few seconds (committing the character). A failure by 5 or more means they fall, become entangled or sink.

