Cool game, Steve, love the starter resprites. Wooper B)
Not a huge fan of the trees, really, but each to his own I guess, they're nice trees but I feel like they don't go all that well with the overworlds. The lab looks a bit spaced out and empty, as well, I feel like you could maybe fix it up a bit by changing the amount of space between the two walls or adding a rug. Other than that, everything looks good, nice overworlds!