FG204

Future Gadget 204, 2nd Edition Ver. 2.31 is, as its name suggests, the 204th Future Gadget to be developed. It was created by the Itaru Hashida of the year 2036.

The Future Gadget is a full-fledged time machine, albeit it is still incomplete and, as a result, only capable of allowing the user to travel backwards in time, as opposed to the time machine developed by SERN, which enabled time travel in both directions. There is one exception to this, however. In the Beta Attractor Field, the time machine is able to travel both forwards and backwards in time, but requires a large quantity of fuel in order to travel.

At first, the time machine plays a backseat role, only being referenced occasionally. This changes in the sixth chapter of the visual novel, where the fact that the time machine is a future gadget is revealed. It is also revealed in chapter six that Hashida left the time machine to his daughter, Suzuha, so that she could travel back in time and overthrow SERN's dystopia.

On the Beta Attractor Field, it is completed to stop World War III and to enter the Steins Gate world line aka divergence 1.048596% where everyone survives and neither the SERN dystopia nor World War III takes place.

In the Beta Attractor Field the time machine was developed by Rintaro Okabe, who gave it a different name - C204. As the future Okabe explained to his past self, the "C" stands for "Christina", a nickname he had given to Kurisu Makise

The time machine of the Steins Gate world line that appeared in Steins;Gate: The Movie - Load Region of Déjà vu was created by Kurisu and named OR204, after Rintaro Okabe.