I don't think time has anything to do with it. Who says you have to fully complete a game to have played it?
Many games, especially ones of a rather retro nature, can be played for short periods of time. You really don't have to sit and play on Zool till you have completed it.
I think in this respect it is similar to a TV series. You don't have to watch every single episode to have experianced it. Watching the first episode of a series is no different to playing up to the first boss on Zool for example.
If you have time to watch Television, you have time to game.
In response to Shoons. That may have been the case a few years ago but now we have on demand cable television, on demand internet television (and streaming e.g. tvlinks), DVDs of television and of course warez. I very rarely watch TV and choose what I want to watch via, alternate sources.
If I want to watch Frasier, I can load up an episode from my PC. If I want to play Zool, I can load that up. I don't think there is any real difference in modern times.