Just gone through Prehistoric Isle (arcade, on PS3)...what a horribly difficult game! Think I must've taken about 30 credits to get through it, the main sprite is really fat/wide, and as the screen is always littered with creatures, it's almost impossible to stay alive for longer than 30 seconds. Remember it being 20p a go back in the day, plus it was offputtingly difficult even back then, plus I was never rich enough to play very far into it. Somewhat bizarrely, the title screen contains the game's biggest spoiler(!)
Still, for the £1.99 it cost, I'm not complaining. There are loads of SNK games in the PSN 'Minis' section, sort of makes me think they were planning a second SNK classics compilation (???) but decided to sell them individually online instead - there seem to be around 12-16 titles on there (of which I've grabbed around 90%, bar the sports ones and Marvin's Maze).