So. Yes. Well, I'm running Rogue Trader, and as an ex-GM of the swashbucklingly awesome 7th Sea game, I tend to go with a far less lethal, more "you're the goddamn heroes, so act like it" over-the-top style of game. If my players want to do something that makes sense, I roll with it, even if I never saw it coming or it derails the plot. My players are aware of that, and generally things work out great. However, I've hit a snag.
The players have managed to find the wreck of a battlecruiser, with a Rome-sized city-state built on top of it. There's another city-state on the other end of the continent, and managed to end a nearly millennium-long war via some rational arguments, and by leveling a range of mountains as a sort of "just making a point" thing. The next problem in their way is an "infestation" of mutants that live in the deep catacombs within the world, who are likely led by a Greater Daemon. My players are thinking that they should personally go into the tunnels and try and seal them. The problem is... these tunnels cross the whole **** planet, and while the mutants aren't that tough, there are a
lot
of them. Enough to pose a significant risk to not just the players, but eventually the folks living on the world, when they eventually surge forth a-la LoTR.
So... I'm trying to figure out alternatives to the players' current plan. Any suggestions?