Doom 3: Mr. Smiley Head's Safari

Doom 3: Mr. Smiley Head's Safari
Doom 3: Mr. Smiley Head's Safari is a hacked modification of Doom released in 1995 by Impact Software.

The game is tangled together into the original DOOM.WAD itself, making it illegal to distribute, not only that, but it also contains copyrighted sounds and imagery referencing various pop cultures such as and, in addition to that all the non-finale maps are stolen and are modified to add huge and unnecessary amounts of enemies, most of the total 27 maps are simply from Heroes and Maximum Doom.

There's no special editing in this besides maps, graphics and sounds. Meaning messages are still in their original form from the original Doom and the automap names remain unchanged from the Doom counter parts as well.

Sprites and graphics
The game contains new sprites and graphics by Impact Software, noticeably made in with the lack of any shading and very simple things being drawn.

There's also new and childish names for each map in the intermission screen such as "My right nut", "My left nut" and "AAAAAAAAAAAAAAggghh!!!!". Plus new graphics for the title screen, the intermissions screens, the help screen, the ending screens and the ENDOOM screen.

Impact Software
Impact Software was a group of teenager hackers with this game being the only thing they've ever made, the credits in the game points out their names and professions as follows :

Main hacker/programmer/graphics designer/artist/sound and music compilation/debugger/beta tester/engine construction : Calvin Wong

Editor/hacker in chief : Ken Wu

Innovation/idea : Anthony Ong, Mike Tam, Jonathan Chang and John Wei

Doom 4 : The Final Chapter
After beating the game there's an announcement for a sequel to be released in 1996, it was abandoned however and never finished.