I like the concept of the game. Reminds me a bit of "There is No Game".
Although the movement was smooth, it felt kind of weird because it continued to move the character for a a split second after releasing the key.
I think the mood that you achieved fits the game and manages to work well with the minimalist style that you chose.
Right before the game closes, I believe an interesting effect to achieve would've been the screens slowly turning off as the game was closed down.
In my opinion, what you created overall in such a limited time is awesome.
Keep up the good work!