You could have your friend that your speedrunning with be a vassal (which is actually fun to do outside of speedrunning), or you could have them play as somewhere else to do specific things. Also, it adds some different strategies to runs. I see this as a way to get multiple people into speedrunning CK2. Now that I have gone over that, I would like to say that I think that they should be allowed, but they should have their own tab. Just have England immediately surrender and you're run is complete.

It's the same situation with Stamford Bridge runs. Meaning that that would cut off 3-4 months off the run. If I had my friend playing Lombardy then he could just surrender right after I declare war on him. Most of that time is spent at war with Lombardy. To give an example, if I were to do an HRE run, that normally takes me about 7 and a half months. If multiplayer runs are eligible runs, this would make runs very, very easy. You can do Ironman Mode in multiplayer and also you can't use console in multiplayer anyways. So it's kind of like an Airbud, as I see it (For context, it doesn't say that it's not allowed, so it could be interpreted as being allowed). I looked into it, and the rules do not specifically say that you can't. He asked me if I knew whether or not speedruns could be done as multiplayer. I was playing CK2 with one of my friends the other day and we started talking about speedrunning.

Is crusader kings 2 multiplayer