> What is the criteria for PC games when it comes to acceptability for MAME? Is there
> even such criteria?
I'd say there wasn't much point in focusing on anything newer than Win9x stuff at most for now, preferably stuff than runs on low-end Pentiums. There's a LOT of that to document, especially properly if we're talking floppy images and such, and it's about the grade MAME is capable of handling right now.
Non-English software should probably be a priority too since much of it isn't well documented (Japanese stuff etc.) and obviously it makes sense to include especially rare / uncommon material regardless.