From the little-known video game Darkest of Days (which had a game engine capable of handling hundreds of AI at once in the same area, interacting with each other and the player, and without strict scripts determining their every move, a requirement to make WW1 and Civil War battles feel more real), the AMP-60. Fires off flechettes instead of regular bullets.
This design combines all of the disadvantages of conventional and bullpup layouts and none of their advantages. On top of that fundamental failure, it is a "cool looks over function" ergonomic nightmare with a pistol grip / thumbhole stock at an angle only a contortionist could use, an absolutely moronic safety switch that is not only pointlessly separate from the fire select switch but also impossible to reach with either hand in operating position, and a magazine change that literally is the worst thing since muzzle loading and would likely require turning the rifle 90 degrees *in two axes* in order to reach.
