Encounter: Bridges

I like making fights interesting by making them take place in odd spots. Fighting on a bridge is one of those things that seems so very mundane, but can have so many interesting consequences. Credit for the image to Reddit user TopdeBotton.


Environment: Forests, Rivers
Theme: Restricted movement, Dangerous boundaries

Characteristics:

• Narrow path to the other side
• Easily blocked off
• Edges are open, people can be knocked off into the water
• Bodies pile up

Uses:

• Choke point for a critical area
• Many mooks block off the bridge, preventing passage
• Aquatic monsters jump on and off the sides

Info:
Fighting on a bridge isn't the same as having an open area, or even a corridor of a dungeon. Falling off is a very real possibility, and potentially a lethal one if the bridge is up high enough. In other cases, falling off would slow someone down immensely, allowing them to be shot with arrows or gutted with spears. 
The main problem with fighting on a bridge is how narrow it is. Like a dungeon corridor, it's easy for one or two monsters to completely block it off, forcing a party to engage in combat. That combat is going to be different from a more open area, and even different from a dungeon. In a dungeon, monsters in the next room are blocked by a wall. With a bridge, that is not the case. Ranged attacks from the other side onto the party are still an option, and the PCs don't have too much they can do about it. There will be a melee combat occurring where the two sides meet somewhere on the bridge, and the PCs will have to consider whether or not they even want to risk shooting bows and spells into it.
Aquatic monsters can add another level of intensity to the fight. If tentacles writhe beneath the party and begin attacking while they're stuck on the bridge, they will be forced to use unusual tactics to survive. If other monsters leap up out of the water and engage in melee combat on the edges of the bridge, only to then jump back in and reappear the next round, then the combat becomes that much more hectic. Non-aquatic monsters may still hang out underneath the bridge, and should be focused on ways to grapple people and drag them off the side.