Nitemare-3D (also known as Hugo 4 or Hugo's Nitemare 3-D) is a first-person shooter developed by Gray Research Associates and published by Gray design Associates and  Accurate Research (in Australia).

The game is a sequel to the Hugo adventure trilogy. Hugo's girlfriend Penelope has been kidnapped by Dr. Hammerstein who wants to conduct experiments on her. Hugo must find his way through Hammerstein's mansion and save Penelope.

On the technical side, the game is similar to early first-person shooters like Catacomb 3D or Wolfenstein 3D. Floor and ceiling are not extured and the level structure is still based on a rectangular grid.

There are few features which hint at the adventure background of the series. There are safes in the game for which you need to find combinations, and while some only contain bonus items, others contain keycards. The game has a focus on exploration. You often can go up and down a various places to enter new areas in lower  or higher levels, to either find bonus items or necessary items. You have got an automap and and enemy radar, but both only work if a corresponding gauge is not empty. You refill the gauge by collecting magical eye balls and crytal balls. The game contains four different weapons. The standard plasma shot works on all enemies, but other weapons are more effective on certain types of enemies.