If your players would never go all out without your explicit go ahead, what's the risk in telling your players that there's an undead game afoot? Also, seriously, the stated premise was secretly Ravenloft game with a rogue. I don't really see the issue with having that be the premise.
So, as long as that's all you need to tell folks, you're fine. However, I suspect that there's lots of hidden stuff that goes unsaid, as you've said as much.Ok, it's not like I don't say that. So....
Flavor and mechanics are really separate things. If you don't like the flavor of stuff, then you can trivially adjust that without ever touching the base rules of the game.Sure, there are just not many with enough flavor.
Given that one of your past examples was a cleric casting silence, and then his god making it shout instead to wake folks up (or the opposite. I don't recall which, exactly.), I think you're wrong on this one. Also, it's not, "Sometimes summoning spells will summon the wrong thing," but rather, "Sometimes summoning spells will summon something that's entirely based on my whim."Only the hyper controlling player with lots of deep personal problems would say my house rules ''control a character''. It's not like ''sometimes your summoning spells will miss summon'' equals ''your character is now under my control and you will do this''.