Episode 17: WAR GAMES
Many consider this the pinnacle of SPACE:1999, not at least the writer, Christopher Penfold, has on numerous occations explained why he felt this was the sort of direction that he would really have liked the series to take.

A resident on the space1999@buffnet.net mailing list, powysbooks@webtv.net, explains why he finds this particular installement so fascinating:

YEA! My impressions of War Games come more from the novelization than the episode (which I did not see on its initial airing). It was, however, the first Space: 1999 story I read, as Lunar Attack was the first 1999 book I bought.

Both novelization and episode have a truly "alien" alien race. That is what I think makes this stand out. They live as units in a collective brain, all their experiences and thoughts being added to the brain. They interact with each other via the brain, and, in a sense, are immortal because all that they are--beyond the physical--lives on. They have no fear because of this communal existence.

Humans, isolated one from the other, who view death as the end, a loss, with fear--would, indeed, destroy their perfect world.

When the aliens say they will not stop him, but then seem to do just that with the planetary defense screens, are not lying. They have set up the illlusion but Koenig and Helena are controlling it to a large extent.

Yes, it was a dream, but I think it works here. As to who experienced the dream, perhaps everyone, perhaps just Koenig and Helena. Perhaps as they were the two main players in the illusion and had contact directly with the aliens, perhaps that is why they remember and the others have forgotten. Or perhaps since Keonig is the decision maker and Helena, an important advisor, perhaps they were chosen to experience the illusion and the others were not.

The whole, "The lights, the colors, could they be a language of some kind" dialogue blew me away as a child.

Also this is a major piece in the MUF arc--simply because Koenig lays it out for us, or at least his perception of what is happening to them.