Id Software

id Software is an American video game development company from Mesquite, Texas, most notable for creating the Doom and Quake series.

Proposed Fallout iPhone game
On November 5, 2009, John Carmack of id Software said that, while it was nothing official yet, he had an internal proof of concept made for a Fallout iPhone game. Both Carmack and Bethesda's Todd Howard are fans of the platform and any iPhone game based on Bethesda's IP would have likely been made as a joint project between id and Bethesda.

Carmack said that he would likely be personally involved in making the game, although he was too overloaded with work on other games. "At the very least I'm going to be providing code," he said. Carmack left the company in 2013, while Fallout Shelter was released for mobile devices in 2015, with later expansions onto other consoles.

Creation Club content
The Creation Club content "Doom BFG" incorporates into Fallout 4 content from id Software's Doom series, such as the BFG 9000 and argent plasma cells with references to the Union Aerospace Corporation.

Fallout 76
id Software provided development assistance on Fallout 76, in the form of additional programmers. Specifically, they assisted with netcode from Quake Champions to support the multiplayer functionality needed to realize the game.