Forerunner Tank

Forerunner Tank was a proposed level in Halo 2 's Campaign that was canceled during the production phase of the game.

Description
The level was only revealed on the Halo 2 cutscene commentary contained in the Halo 3 Legendary Edition's first Bonus Disc. The purpose of the level was to tie in plot between the end of the level Regret and the cutscene after the end of the level Quarantine Zone. The level was said to be placed after the cutscene in Quarantine Zone where the Arbiter is pushed down the index chamber by Tartarus and before the cutscene where the Arbiter meets the Master Chief and talks to the Gravemind.

The level would have described the Master Chief's adventure through the bowels of Delta Halo before his eventual capture by the Gravemind; the "Forerunner Tank" providing the namesake of the level was only described as something "... Awesome, that blows things up, glows a lot from little windows and moves real fast." The level's replacement was the short cutscene at the end of Regret; the level's removal resulted in the long series of different cutscenes between Quarantine Zone and Gravemind.

Trivia

 * Bungie was planning to use some geometry that they had previously used on the gondola.
 * This level was supposed to be the Gravemind's introduction.
 * In this level, the Gravemind's tentacles were going to slam down all around you and move behind doors like racing freight trains.
 * When they asked Jason Jones why he wanted it in the game, his only words were that "awesomeness would ensue".
 * This level would also have been the only time that the Master Chief encountered Sentinels in Halo 2.