Impossible Mission for me; didn't realise that it's actually a good game. Very very good for the time too.

I love the game, but it was truly impossible back then (pirated, no manual, no idea what I had to do) and even today, with an emulator and every hint on the internet ;)

I know it's not actually impossible, some people finished it, but I never have.

Bruce Lee and The Last Ninja though, I can finish either with my eyes closed!