LostSoul
Adventurer
Not everything has to perfectly laid out before you. You can just play it by ear if your players trust you. If the PCs set of an alarm, say, you can just say that the other NPCs show up in 6 rounds. Or something like that.
One way of dungeon mapping is to draw a flowchart. Just link the important encounter areas (not just rooms, but passages where something might happen). You can then focus all your energies on developing those few areas.
(I don't actually use this method because I like to draw out the maps; but when I've GMed Star Wars games I never have a map, just a general idea of where things are.)
As far as having something shadowing the PCs, have them make Spot and Listen checks (and oppose them with the NPC's Hide and Move Silently). Just the fact that they have to roll will add tension to the situation. (Don't assume the PCs automatically fail, either - you'd just be ignoring the abilities of the PCs, something they've worked hard to build.) Describe barely missed/made checks as "something in the shadows; it's gone now, maybe it's just a trick of the light" or something like that.
One way of dungeon mapping is to draw a flowchart. Just link the important encounter areas (not just rooms, but passages where something might happen). You can then focus all your energies on developing those few areas.
(I don't actually use this method because I like to draw out the maps; but when I've GMed Star Wars games I never have a map, just a general idea of where things are.)
As far as having something shadowing the PCs, have them make Spot and Listen checks (and oppose them with the NPC's Hide and Move Silently). Just the fact that they have to roll will add tension to the situation. (Don't assume the PCs automatically fail, either - you'd just be ignoring the abilities of the PCs, something they've worked hard to build.) Describe barely missed/made checks as "something in the shadows; it's gone now, maybe it's just a trick of the light" or something like that.