Thank you for the kind words. I'm having fun working on it, though I'm looking forward to wrapping it up so I can get on to my next one.
I'm building a set of haunted house themed levels at the moment. My intention is that each block of 4-6 levels will have a different theme, representing the different dreams he's traversing. The one in the screenshot is from the castles and caves series. In addition to the already built castles & caves and the WIP haunted house set, I'm planning on a set of futuristic & factory levels and one other set. I'm undecided on the last set. I'm leaning toward either something pseudo historical, like ancient Egyptian or Mayan, or something completely off-the-wall like food-based levels. Food sounds sillier so I will probably go that way. If it makes my kid laugh, it makes it into the game.
The enemies basically stay the same, but are modified to match the level theme. In the standard castles and caves, the enemies are the little purple ant guy you see there, a blob guy, a ghost, and a goofy (but dangerous) carnivorous boot. For example, the haunted house levels will have a little scarier version of the ghost, plus comically horror-fied versions of the others (zombie/Frankenstein boot, vampire ant, mummy blob). The futuristic one might have them turned into robots and/or aliens (evil Terminator boot, for instance). You'll still be able to tell by looking at them what their base version is, that way you know how to handle them.