I should someday introduce you all to Rampant Griffon (an RPG I wrote 20 years ago, that we played for over a decade at my store). It's got "12-bit" rounds, and a "bit-timer" (at the table, it's a cardboard clock with the long hand counting "bits" and the short hand counting rounds). Every action has a speed (in bits, you see). You're always allowed to do actions that go over (if you start at, say, 11, and do a 6-bit action) but then you have less time next round. (Once you pass 12, your turn is done). Of course, you roll for defending in that game as much as you roll for attacking (and defending takes time too... a character that isn't attacked can do more things in a round). Combat in that game was extremely cinematic.You could "balance" it by having number of "parts" in the round say 10
Then your speed becomes 1/10 (you act in each segment), 4/10 (you act 2 times in the first round, 3 times in the second at segments 4, 8, 2, 6 ,10) etc...but that becomes an arms race where having faster speed is advantage over any other consideration
Yeah, defending (like blocking with a shield) did anti-damage against incoming attacks, but you could also shield-bash. You could parry with your main weapon, too. (Or chose to "take" the hit, if the damage was light, so you'd have time for another attack). I guess that's kind of like everyone having reckless attack. There weren't any classes (just skills - you could make any archetype you wanted). The game was very swingy from a modern game design perspective, though. Not very balanced, but always very fun.Gurps has something similar with active defense, rolling against set number which depends on your skill with the weapon/shield.
I like thi bits idea, you could forego defense to have more bits for attack (all out attack) or vice versa
Expedition Retreat allows you to Dash as a bonus action.