Many years ago, Cave posted an April Fools joke on their blog: namely, Deathsmiles as a platformer, as seen here.
Cave has recently resurfaced the original zip on Facebook for your playing pleasure:
http://de-o-smiles.cocolog-nifty.com/blog/files/0401.zip
Feel free to try this rare piece of videogame history~
Mushihimesama will be released on Steam in Winter 2015.