The “Team RayCast” has released a special mod of Wolf3D and SOD called “SplitWolf” where 2 players can cooperate on the same game in split screens in order to defeat nazis!
From the description on their website:
SplitScreen for up to 4 players (currently optimized for 2) in cooperative mode on a single PC!!! (SDL) Support for both vertical and horizontal splitscreen and many special cooperative game modes that add endless replay value and tactics to classic maps. Minimap/radar support. Support of Wolf3D and Spear of Destiny (none of the original files included in the pack)
You can see the mod in action in this video: