One of the things that I struggle with playing Total War Warhammer is how I really bite into a faction and I totally burn myself out on them. To prevent burn-out, I'm trying to swap between factions more regularly, but I find that the manual swapping of factions to keep up the amount of variation is kind of cumbersome.
So, I came up with this mode idea. I've considered the following names; "Advisor" Mode, "The Grand Tour" Mode, "Tourist" Mode, "Turncoat" Mode, "Episodic" Mode, "Your Own Worst Enemy" Mode, etc.
Here's the logline; "At the end of every turn, rather than wait for each faction to make their own move, your faction rotates to that of the next playable faction, allowing you to try new factions and experience new mechanics at a regular interval."
My theory is that, by implementing this mode, you keep players engaged for longer and possibly engaged with their world's story for longer as well. They wouldn't just think about the factions as 'AIs', but as their own factions with their own imperatives. After all, YOU set those imperatives and you get to see how that plays out.
The way the selection screen would work is that, rather than picking one faction, you mark on a checklist which factions you'd like to rotate between. Maybe there's a limit the devs would have in mind, like "you can only rotate between 10 factions", but I leave that up to discussion. This means that you might choose to play all of the Lizardmen factions, but nothing else. You could also play every single faction you can play, if you wanted to (and were prepared for a long haul).
Alternative to all this, perhaps the mode instead gives you one random faction per round of turns and the rest of the factions are continued by the AIs.
Q: What happens if the playable factions collide? You can only command one army?
A: You play the faction who's turn you're on and you give it a good faith try. Heck, if you don't want to give it a good faith try and want to mess around and play favorites, why not? It's a game, after all.
Q: But then, why would you make large armies on any of your factions, if you're trying to beat yourself?
A: If people play this mode, I would assume they have willingness to "kill their own babies", as said in the words of famous writers. And for the players who wouldn't like to go that far, they could always stop.
Q: What would the win condition be?
A: It will be different per faction following the same win conditions of the Mortal Empires campaigns. Though it would be nice if it's possible to review how close other factions are to completing their own win conditions and encourage you to challenge them and keep yourself on your toes.
Q: What would the diplomacy be like?
A: I would still make it so that the diplomacy stays the same, but it would be nice if a history of treaties was clearly visible whenever you engage with a faction. That is something I've wanted in the base campaign mode, but I think that some memory aids to stay 'in character' would be nice. For example, if I were playing a skaven side and I was offering peace to a Lizardmen side for enough money and plan to betray that Lizardmen side, I'd want to stay in character as the Lizardmen and remember to honor the peace to keep my reliability rating high.
Q: What about factions that are destroyed or don't appear until later?
A: Some factions would enter and fall out of the rotation, depending where we are in the campaign. That means that it might be a long while until you can play Chaos. On the other hand, you may end up wiping out factions early. For example, if you ran a Beastmen horde and that horde was destroyed early on. Those could return through uprisings, potentially.