Nesteris, that's interesting - I haven't checked that out... but actually I've fixed the geemers, didn't use 8 direction or platform, just ended up retooling my engine. It actually works better than ever, and is framerate independent. Much respect to the developers of the 80's, some of these enemy behaviors are more complex than they seem!
A quick update - didn't upload a new build, but here are some screenshots. New additions include:
Several New Enemies and Behaviors (see screen shots)
Zone scrolling camera movement for specific rooms (see screen shots) - which addresses the issue of not being able to see where to jump vertically in certain situations
Improved game-play elements, such as marking enemies that need to be eliminated
Thanks for all the feedback everyone!