Once you do the research and weed out different region titles, dups and such, there are about 1000-1500 for the major consoles(nes, snes, sega). A lot of the categorizing could be done by screenshots, maybe 50-75%. The remaining games or ones that are questionable from shots would just need to be played for 5-10 seconds
Yes, it would take a while to get something usable, but it doesnt seem impossible