Opus 5.5 one-shotted a Roblox anime brawler

The constraint is the interesting part. "Built only using toolbox and nothing else" means no outside asset packs and no separate art pipeline — the things Roblox games normally reach for the moment a character needs to look like anything.

Opus 5.5 produced a Smash-style anime fighter anyway. The author says he is "genuinely blown away by how much detail went into this," and calls it "leagues above Fable."

Fighting games are an unforgiving demo. If a hit does not feel like a hit, you notice within a second, and no caption can argue you out of it. That is why this one is worth watching rather than just reading about.