i think you need to tweak the styling a bit, even if you create an entire theme of doodads in this style it doesn't look like hammer watch the edges and details are 'blurry' and need to be a little bit sharper.
hammer-watch uses solid colours to hide the edges of walls outside of a level, but if your careful and make some 'outside' walls you could use parallax's to add space to the background
re-texturing the player sprites will also add to the feel, you could replace the rangers arrows with bullets, make the wizard into a flame thrower etc.
i am moving this thread into the resources section as it is not a custom map.
