An interesting game for sure, with a lot of visual effects that I got no idea how to do.
However the actual graphics felt weaker than the rest of the game.
1) for the castle either change the cell size from 16x16 to 14x14 or expand the cells to make them properly fit together
2) you got those really cool composite space wizards - do something similar for the main character and planets; you can then also make a really cool death animation for the player exploding into multiple parts :)
3) the castle walls are too bright and unpleasing to look at
4) the meteors... they don't look good
Also, a minor thing - if then dying your body collides with other things that would kill you, the death sound is played again, which probably shouldn't happen.