A: Andy says: The simple answer is because Doctor Who is not a time travel show.

Oh, it pretends to be a time travel show, and sometimes it does have time travel of a sort, but Doctor Who is a show about monsters, not time travel. It’s about a time traveler who fights off invading monsters using any means other than time travel.

Never does The Doctor solve their problems by saying “No problem, we’ll just hop in my TARDIS, go back five minutes, and have another bash at this.” It’s literally forbidden by the in-universe rules of how time travel works. The Blinovitch Limitation Effect is why the Doctor cannot encounter past or future versions of themselves (except on rare occasions when the writers don’t feel like following their own rules because they want to do a multi-Doctor reunion show or something).

Actual time travel shows are about changing history — something The Doctor cannot do. Instead The Doctor talks about “fixed points in time” which cannot be changed. The Doctor never deals with temporal paradoxes or alternate realities created by splintering timelines. The Doctor simply uses the TARDIS to go to different historical settings in which to fight off invading monsters encountered there, wringing their hands sadly when things goes wrong and someone can’t be saved.

One notable exception is Doctor Who’s all-time best episode, Blink, but even then, time travel is used in a very minimal way. Instead the focus is mainly on that episode’s invading monsters, the Weeping Angels.

Doctor Who scholars are welcome to tell me where I’m wrong here, and I acknowledge that my knowledge is incomplete, but I can’t think of a single example of a Doctor Who story in which we see events unfold two different ways, before and after time travel interference.

So when people say Doctor Who is the perfect subject matter to turn into a version of Chrononauts, I say, how so? What events would I put on the Timeline?

The true “perfect subject matter for a Chrononauts game” was of course Back to the Future, since it’s all about showing us the before and afters of time travel tampering, which are what I need for the two sides of the cards in a Chrononauts game. Same thing with Star Trek, whose many time travel episodes are all about showing us another reality, which was the result of a specific change to events in the past, and how that change to the past must usually be reset by the end of the episode, so that reality ripples back to the way things had been. When does that sort of thing ever happen on Doctor Who? And without that, how can I make a Chrononauts timeline about it?