Oh boy, this is my first rating of the jam and what an experience it was!
First off, the game is long. I played for over an hour and didn't finish it yet. Although I'll be coming back to this one. (too many games to rate and so little time.) It's a metroidvania style game in which you hack and slash your way through several rooms and corridors, find upgrades and backtrack to progress.
The art and style of the game really did it for me. I thought they were great. The animations of the attacks stood out especially. Very minimalistic approach but you did a lot with very little.
The gameplay was a really smooth experience, with the directional hits, combined with the wall jumps making for some really skill based progression. It just feels cool moving around in this game.
As for the secondary theme, I didn't notice a lot of it. It is of course woven in to the story and as I said, I didn't finish the game, so more of the theme might be obvious deeper into the game.
Very solid soundtrack and sfx, although the sound did stop completely at seemingly random times for random durations. Didn't happen that much as to be an issue.
Although some of the animations (like the double images behind the main character and the after death particles of the enemies) didn't look very "gameboy" to me, it amazes me what you've been able to accomplish in only 10 days, with the limitations that were put upon us. If this first game is any indication of the average quality of the Jam, it's going to be a hardfought competition!