I really fw this kind of vibe, the visuals and music are hard as hell, but there's not much to say about game design, sound effects, or overall polish (which is totally understandable to some extent)
Does this game really only rely on WASD and time based weapons? I didn't really understand how to aim with the sword or the fireball thing. I also found that this game can be completely cheesed by standing right across the enemy spawnpoint, which is ridiculously easy to pull off. 
Other than that, I'd add some audio feedback for hitting an enemy and a score counter, or maybe even a win screen. I won't talk about bugs and how the basic enemy can get stuck to you (super common bug, or feature?) since yes, this is a gamejam game, but if you're gonna come back to polish this, please add some more content. I love isometric stuff and even more do I love this kind of graphic, and I'd love to see where this game goes!