I really, really enjoyed my visit to Game On. That was easily about 7 stars. Of course, as a person from the US I never see exhibits with valuable items you're allowed to touch. It was such a thrill to play Pac Man and Pong and Galaga.
The upstairs exhibits are great also, but really in poor repair in some cases. I've been to very similar places in the US which were better maintained (although not bilingual).