Expansion to Nemesis. Combat will be very different from Core Box. It will force players to take much more active approach - you need to make sure that whatever will be on this ship will not evolve beyond its current state.

It will still not be a combat game, but a survival one, but the feeling will be very different. You will want to fight and make sure to kill (and then double kill just to be sure), instead of mostly run.

All in all this expansion will be designed in a way to give you constant pressure between trying to meet your goal and managing Carnomorphs on the ship.