I disagree with franktech, there’s game jams on this forum that have solid prototypes within 3 days to a week. There’s some featured from the weekly streams Epic MegaJam Winners 2015 | Project Spotlight | Unreal Engine - YouTube
Obviously they are super rushed, but they are playable, and some of them manage to have multiplayer, a nice art aesthetic, or interesting game-play, even within that strict time crunch. You could probably modify the shooter template and have spells/melee/archery within a day or two. It’s not going to be a polished or pretty vertical slice of the final product, but in my opinion, you should have a really rough prototype, then do a more polished vertical slice type prototype.