Ro Sham Bo is an old school Halo 3 custom game that featured random weapons and Foundry's simplistic back hallway. The mode is essentially fiesta in a confined space. There are several way to play Ro Sham Bo in Halo 5.
Ro Sham Bo - Random weapons, one life, breakout style
DL Link: http://tinyurl.com/h4oh2xj
Ro Sham Blam - Grifball on Foundry's back hallway, a clusterfu*k
DL Link: http://tinyurl.com/j8p237j
Ro Sham Fam - Random weapons, infinite lives, three strongholds
DL Link: http://tinyurl.com/zgtwb9w
Christmas CTF - Random weapons, infinite lives, two flags
DL Link: http://tinyurl.com/jks9ydp
The fun in this map is its simplicity. Foundry's back hallway provides a fun space to try and outmaneuver your opponents as rockets and bullets fly by. The map itself was built specially to replicate the area on Foundry as closely as possible. I've tried to add as much detail as possible to imitate not only the gameplay but the atmosphere of the original playspace.
Short clip of gameplay: http://i.imgur.com/aZFMy5Q.gifv