Arena Rex 35mm gladiator miniatures game. Three to six fighters per side - an army I could actually finish painting! Of course, gladiatorial combat simulation games aren’t new.
As I have mentioned before, heroes forced into the arena to fight and/or die is one of the classic bits of genre fiction. Gladiators are the biggest and flashiest example in our history, up to Spartacus nearly bringing the whole empire down.
It happens to Conan and John Carter, Han Solo and Chewbacca very early in the original Marvel comics and then Luke, Obi-Wan, Anakin and Padme on screen... It’s a popular side plot for prison adventures too.
RPGs have featured these in adventures, and Eternal Contenders is all about gladiators and their managers - following the boxing-based Contenders, as stories of fighting sports use a lot of the same tropes throughout. There’s a Hillfolk series pitch for it as well.
Ever sent your PCs into the arena? If not, why not? (I never did in TWH because Angel did that one already.)