Creator update note:
I've now playtested this with up to 6 players.
A 4 player "battle royale" wrestling themed one shot ran for 2 hours flat, with a variety of archetypes. In 5e terms, at 50 HP that was 4 level 6 fighters.
The last player standing had about 12 HP left, and I was fairly free with Bonus awards to keep things fun.
In theory, if one slotted this into a storytelling system, you could do 1hr RP and have a 2 hr combat session. Or a smaller encounter to flip it.
It's very freeform, and lent itself to quick combat riff ideas. The players were engaged, and enjoyed getting to roll dice all night. The system lends itself to cinematic storytelling, with a GM helping guide the setting.