What was your hardest rom to find?

i've never had any probs except probably the first day i got into emulation.what with winmx and direct connect i found everything quite easy.regarding radiant silvergun it is supported in mame but is classed as unworking at the moment...the rom should be easy enough to find though....stv emulation seems to be one of the mame devs priorities at the moment so i can't see it being that far off being playable.garoun.zip does exist....just look using the above programs.
hullcityfcmad