Heya! The character is cute, reminds me of Gussun Oyoyo. I did some edits:

Palette: I toned down the saturation on the sky blue. Saturation is a great way to give visual cues to the player, important things like your health bar, character and things he can interact with should be very saturated to make them "pop", while far background elements are less important (strictly gameplay-wise) and should be toned down.
I illustrated on the tile the ambient light's colour (the sky) will be reflected onto the shaded parts, and should be hued blue; the highlights should show the pure (white) light.
Tiles: Honestly not that fantastic at them myself

Though your tiles are quite large, you can pack a lot of detail into them if you want, like the teleporter half I tried.
Character: Fixed the head a bit, adjusted the palette a bit. Made the legs less stick figure-like, added a bit of detail. Again, he's quite large.
Also I kinda like him without arms
