I'm so amazed something like this has been obtained and preserved. I thought this was just another review copy or demo version that resembles the final game but nope, this is some real deal work in progress material. When Baladium exploded I was like "Oh, that's different then the other boss explosions" but then that floating orb appeared and a second phase of the fight began, my mind was so blown that the boss killed me because I wasn't expecting it. (The game's concept art showed this creature and yet I didn't actually think they programmed it in at one point!)
From the not-yet-refined music, to the changed sprites and textures, this prototype is like opening a treasure chest.
I also did a stream of me playing through the prototype!
If only we could figure out those inaccessible debug options but they might have only been accessible by the devs with their dev kits or something.