Minor scrapped Call of Duty 4 missions

Strike
Strike is an abandoned single-player mission in Call of Duty 4. It never existed in any playable form. The only evidence to prove it ever existed is a file called "strike.vision", which was discovered in the game (alongside the .vision files for all other levels in the game, both multiplayer and single-player, including many abandoned missions and maps).

Due to its name, it can be assumed that it is the single-player counterpart to the multiplayer map, Strike.

Rivertown
Rivertown is an abandoned single-player mission in Call of Duty 4. It never existed in any playable form. The only evidence to prove it ever existed is a file called "rivertown.str", present in the game's mod tools under the directory "raw/english/localizedstrings." Due to what was most likely an error on Infinity Ward's behalf, he string file itself is a shortened version of the string file for Parabolic.

Zipline
Zipline is an abandoned single-player mission in Call of Duty 4. The only evidence to prove it ever existed is a file called "zipline.str", present in the game's mod tools under the directory "raw/english/localizedstrings." Due to what was most likely an error on Infinity Ward's behalf, he string file itself is completely empty.

In the game's level editor, prefabs from a folder called "zipline" can be placed; they are mostly identical to the prefabs from Blackout and Parabolic.

Textures for the intended skybox of the level are present in the game, and they were put to use serving as the skybox texture for Blackout.

Wetwork
Wetwork is an abandoned single-player mission in Call of Duty 4. It never existed in any playable form. The only evidence to prove it ever existed is a file called "wetwork.vision", which was discovered in the game (alongside the .vision files for all other levels in the game, both multiplayer and single-player, including many abandoned missions and maps).

Despite its name, it is not the console codename for Wet Work or Crew Expendable. Wet Work's console codename is "mp_cargoship," while Crew Expendable's console codename is "cargoship;" Wetwork is a completely different level.