Fortunately, so-called 'abandonware' - old games that are supposedly legal to download for free - is astonishingly easy to come by on the internet. However, in most cases a given game hasn't been signed off as abandoned by its creator, it's simply that its creator hasn't been/can't be contacted for permission.

Just a couple of years ago you could turn up pretty much anything with the slightest spot of Googling, but publishe