Chrono Trigger: Crimson Echoes is a fan-made game that was originally set for release on May 31st, 2009. Work for it began in 2004. However, on May 8th, 2009, Square Enix sent out a cease and desist letter to Chrono Compendium.
The game was designed as an interquel between Chrono Trigger and Chrono Cross.
Shortly after its announced cancellation, the group members of the project have begun "The Month That Could Have Been" starting May 31st. To read more about the Crimson Echoes discontinuation and basic information, it is recommended you visit the site by ZeaLitY, one of the game's creators. 
Crimson Echoes takes place right after the events of Chrono Trigger in the year 1005 AD It starts where Marle and Crono are discussing the big tomorrow. Marle drilling Crono's head not to sleep in. They kiss and make their way home. Crono (Still living with his mom) is yet again forcibly to wakened, but this time by Marle.
Crono, Marle, and Lucca attend an important meeting at Guardia Castle between the nations of Guardia and Porre. Porre has grievances of some kind and some political mumbo jumbo goes on. After a suspicious encounter with the Porrean agents, our three heroes are caught in an unstable Time Gate generated by a Time Egg replica. They all share glimpses of events across time featuring their old friends, then find themselves greeted by Robo in the year 2305, who is assisting Belthasar in his hidden facility. And so the untold story of the eternally burning flames begins...
Playthroughs of development versions of Crimson Echoes have been released via a YouTube account.
In honor of the "Month That Could Have Been," the developers of Crimson Echoes produced a video walkthrough of their '98% beta, the version being worked on when Square-Enix issued the C&D, complete with director commentary. It can be viewed on YouTube on the user page of CEMemorial or by going directly to the playlist.
The 98%-ish complete beta and an earlier version were eventually leaked and made playable. Soon afterward, an unofficial restoration effort is known as Chrono Trigger: Flames of Eternity became popular and aimed to fully complete the game's development, switching from using the earlier version as a base to the latest released version. While it received heavy criticism from the first developers and a very mixed reaction from the fan base for some of the changes, it nonetheless is the most stable version of the game and is under active development.
In addition to Flames of Eternity, there are rumors of a "100%" Crimson Echoes ROM circulating that contains the planned sprite changes as seen in the bonus CEMemorial video. The true existence of this version is unverified and it is unknown if it contains any of the leftover glitches that Flames of Eternity fixed, though it is possible that it is the result of another unrelated restoration attempt.
pseudo-canon of Chrono Trigger: Crimson Echoes.