MNblockhead
A Title Much Cooler Than Anything on the Old Site
Currently I'm running a notoriously deadly mega-dungeon. Rappan Atthuk. There are a few times when only two could show up and I didn't run anything differently. It is up to them to play differently. Some of these were among my favorite games. The fear and anxiety is ratcheted up. Players rely more on careful planning and stealth. They know that head-on combat is highly likely to result in death if they don't have a backup plan and a means of escape.
But my players are experienced, which is not your case. Instead of changing the rules or spending time reworking all the encounters, you could have them play several levels above the recommended levels for the adventure you want to run.
But my players are experienced, which is not your case. Instead of changing the rules or spending time reworking all the encounters, you could have them play several levels above the recommended levels for the adventure you want to run.