I usually use unfinished stuff from my dead project in some other projects, so I don't have much of actual unfinished content right now.
Here's some interesting unfinished projects
1.Black & White World mod. I got highly inspired by Half Quake (A famous HL mod), so I decided to make a similiar thing for Duke. I only made four playable levels. Most of this stuff was later used in my later projects, such as opening for a.dream 2. The second level of this mod was used in IIT TC
The mod start with a car crash on the highway in the middle of the night. Duke enters a mine, and then he discovers a teleport to another dimension.
One of the levels actually offers a player a four ways to die. So, if you don't want to play this mod anymore, you can choose one of the four teleports and die a horrible death. First door leads to a tunnel where the player gets smashed by a train. The second leads to a sector filled with water. The third leads to switch, which kills the player, and the fourth drops the player from high hight.
In this mod Duke has a weird weapon called The Cube. It just shoots cubes and freezes the monsters (The Cube replaces the Freezer sprites)
The last map has a small spinning labyrinth
2.Link The Faces of Evil mod
My attempt to make a 2d sidescroller on Duke engine. I used a lot of sprites from Zelda CDi games.
3.Altair mod 2.0. This mod is inspired by Doom weapon wads, with random spawning monsters and weapons. You can also choose characters, and it adds some civilians to the game, which randomly spawn on the levels