I like the visual style, it had a cute simplicity to it.
Fun bug: using the left and right arrow keys moves you faster.
When doing a pixel game, in general, you want all the game assets to have the same pixel size. Use your player asset as the reference size, and redraw the rest to match it. Do not use scaling unless it's a multiple of 2, and then, for effect, like at the game-over screen, it was a nice touch.