So "an ice cube's chance in Hell" isn't a good enough approximation?

From my personal condition, having two eyes that focus in totally different manners and uncoordinated hands to go with them, my ability to shoot down Space Invaders or whatnot, zooming around on a screen at Ferrari-speeds, is pretty much zero. And observing other people often in casinos - handicapped, mentally out of it, and even blind - I would say many "guests" would be in similar straits.