3eish draft - action sequences

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. 

why?

So, my starting place is the mess of action types that exist in the d20 system and its many direct and indirect heirs. Certain editions were clearly worse for this than others; PF2E is probably the best high-crunch solution to the problem, but in my book it shares the problem of needing to spell out exactly how many segments any particular action takes.

To me, the most attractive thing about this action economy is that I do not need to spell out what type of action any given thing a character or monster does is. That's a huge win for naturalistic language. Furthermore, "action" and "turn" become synonymous and I can even reserve "turn" to describe procedures like dungeon or wilderness exploration if I choose.

My hierarchy of short units of time for this game becomes:

• an action
• a few seconds (the entire round)
• a few minutes (too long to do in combat)
• a few hours (too long to do in the middle of exploration or a similar activity)