Well, before anything else, I'd like to volunteer my help.
I found this page:
http://guttenbrunner.com/videopac/o2emPort.html
with info on how to compile O2EM, but I couldn't find the referenced Direct X MingW file, and haven't been able to compile from source.
Heres a short list of what could be addressed:
- there are still some games that aren't working correctly, like Wall Street and Frogger
- sound needs tweaking (I'm guessing correcting the noise recycle in the 8244 emulation should hopefully fix that)
- voice emulation is sample based and some samples are missing (I don't have a Voice to grab the correct samples - MAME uses SP0256 emulation instead of samples)
- there are timing issues, so the compatibility with the actual console is flaky: software that runs on O2EM doesn't always run on the actual hardware, so it's not much help for game development.