Hi there,

the next adventure will start in a larger abandoned building and the PCs fortify themself in this building. Of course, a division of the Empire tries to reach the PCs but they have time to prepare traps. How would you handle an adventure like this?

First thoughts:

1. As the GM determine (behind the screen) what Imperial forces are going to advance/enter from where.

2. Show the players the layout of the building and have them decide where to stage their final stand. Prepare that location for a final combat encounter.

3. Give the players a time frame to set up traps/distractions/obstructions, and let them prepare those (no rolls yet, just determining dice pools). Give them the opportunity to be creative in what skills they can reasonably justify; the more diverse, the better.

4. When they're done, modify the attack plan from step 1, but only as far as those modifications are obviously (e.g. blocked entrances) necessary to the Imperial commander.

5. Have the Empire enter as planned and the players roll for their installations, at the very moment they're hit. You can either tell them the exact outcome of each roll or only the sensory impressions the PCs actually get.

6. Have the Imperial forces show up for the final encounter in the numbers, from the directions, and at the times defined by the dice rolls in step 5.

Or something...

That's pretty well thought out. I might have to steal this and use it on my players at some point.

You could even treat this as a mass combat scenario. Each of the traps can modify the mass combat roll. Each phase is a location as the Empire closes in.

This almost seems like an opportunity for the tables to be turned and for the players to have the map of traps etc. and for the GMs forces to be surprised. Not sure how that would work exactly but it would be an interesting session

Maybe if you're looking for a one-off adventure, reverse the rolls. Players are hired to find a lost (mischevious) child. Hilarity ensues (maybe?).