I like what you did here. Very coherent entry with fitting music and visuals. I think most of the feedback already pointed out some of the issues, but for it was missing some kind of checkpoint or system to make you progress.
I tried to reach the end a couple of times, but I just gave up due to some difficulty spikes - which are to be expected in a jam, so no worries :D
I'll be checking this out again if you plan to do some small QoL updates.
Also, regarding the companion aspect - I was not sure how this was implemented. My take is was that the brother was both companion as well as the opponent?