Development

The development behind The Last Guardian is a complex story, arising largely from earlier games in Team Ico's history.

Conceptualization
Last Guardian is partially based on the interaction between the protagonist of Shadow of the Colossus and his horse, Agro. Much like Team Ico's titular game Ico, the concept of a follower who plays a central role in progressing the story and gameplay was a huge driving force in the development of The Last Guardian; lead designer Ueda stated that the interaction and relation development, especially the development of "emotional attachment" between main character and side character, would play a huge role in The Last Guardian. Similarly, the concept of climbing a mammoth creature would carry over to Trico itself, and is considered by many to be a combination of the mechanics in Ico and Shadow of the Colossus; Ueda has stated that "there's a bit of each of those [games] in there".

Trico
Ueda has stated that he wants Trico to behave as realistically as possible (at least for an animal that doesn't exist), detailing that he wants to avoid "the unnatural idiosyncrasies of the virtual animal" which occurs in most games. When developing Trico, the designers purposely made the animal a bit strange, stating that the design was "deliberately unbalanced because looking strange was important here". Certain interactions and subtleties were added to Trico early in development, such as facial tics (similar to those a cat would make when being petted, challenged, etc.) and detailed keyframes for motion as opposed to the industry standard motion capture, which lent an eeriness and serenity to earlier character models.

The Boy
The "main character" of The Last Guardian was also considered early in development; fluid motion and subtleties became even more important, because gamers often inject themselves into human characters, making subtle movements (such as the fact that when near a wall, the Boy will place a hand on it for balance) important for absolute immersion. Life-like animations, accurate rendering models, and even the sex of the character were hard thought and heavily-developed aspects of the early game.

The Engine
The engine for The Last Guardian features a full physics emulator, a departure from earlier Team ico games. Ueda has stated that the trailer, in which a boy throws a barrel at a creature, who then bites and destroys it, was fully seated in that physics engine, and was used as a test to demonstrate it's power. The engine also includes versions of the previous AI systems used by Team Ico's games, but with an advanced interlocking system allowing for more complete artificial intelligence. Ueda has also stated that the engine renders the effects of wind on each of the creature's feathers.

Development and Marketing Cycle
The following events outline the development and marketing cycle of The Last Guardian from the first announcement up until the most recent events.

2007

 * February 2007 - Team Ico discusses their new title in various interviews, and suggests that they are in the very earliest phases of design.
 * May 2007 - Sony confirms that Team Ico is currently in the development phase for two games - one of these was likely The Last Guardian.

2008

 * January 2008 - Team Ico releases the first teaser image for The Last Guardian.
 * August 2008 - Team Ico is working on The Last Guardian. Fumito Ueda sates that the project is still in work. Shuehi Yoshida states that "Team Ico has something really, really good on the way," on August 4th. On August 28th, Yoshida again tempers expectations by saying "The project isn't ready to show at TGS 2008."

2009

 * March 2009 - Ueda states the game will be in the spirit of Ico.
 * May 2009 - "Project Trico" footage leaks online.
 * June 2009 - Sony shows an extended version of the leaked footage at E3 2009, and announces the game as "The Last Guardian" . Ueda expands on the gameplay concepts behind The Last Guardian.
 * September 2009 - Team Ico present The Last Guardian at Tokyo Game Show 2009

2010

 * February 2010 - Ueda says that more information about The Last Guardian is on the way, but that they don't have new information right now.
 * June 2010 - The Last Guardian isn't shown at E3 2010, sparking rumors that the game might have stopped development.
 * September 2010 - The Last Guardian is shown at Tokyo Game Show 2010, assuaging cancellation fears. For the first time, a release window is given - Holiday 2011 . Ueda details some gameplay features.

2011

 * March 2011 - Team Ico admits that The Last Guardian was supposed to have a demo included with the Ico/Shadow of the Colossus Collection, but that a build wasn't ready for mass market.
 * April 2011 - Ueda delays The Last Guardian past Holiday 2011.
 * September 2011 - The Last Guardian fails to show at Tokyo Game Show 2011, with Sony citing the team's effort to deliver "the very best gaming experience possible" as the reason for the development push.
 * November 2011 - Ueda leaves Sony, but stays on The Last Guardian as an independent contractor.
 * December 2011 - Sony confirms the project is not cancelled and that Ueda is still on the project.

2012

 * January 2012 - The Last Guardian development is moved from the Playstation 3 to the Playstation 4.
 * February 2012 - Yoshida notes that development is "tough", that the cycle is "progress, but slow progress". He notes that some things have been changed or cut, saying "there's some scrapping and rebuilding - iteration in the process", and that the project is "still a really important project". Sony enlists Sony Santa Monica to finish the game.
 * June 2012 - Yoshida states that technical difficulties prohibit showing The Last Guardian at E3.
 * August 2012 - Sony re-confirms trademark registration, says the game is still in development. Yoshida notes that Sony Santa Monica and the team has "had to redo some of the work [the team] had done."
 * Novemeber 2012 - The Last Guardian does not have a showing at Tokyo Game Show 2012. Yoshida states that he can't commit to a 2012 or 2013 release date.

2013

 * February 2013 - Rumors circulate that The Last Guardian is now being developed for PS4, instead of PS3. Ueda confirms that the game is being developed, but is waiting to reintroduce the title.
 * June 2013 - The Last Guardian doesn't show at Tokyo Game Show. Jack Tretton states the game is on hiatus, but Yoshida replies that the game is "in active development".
 * August 2013 - Ueda states "The Last Guardian is still in development, but other projects such as Puppeteer and Knack currently taking higher priority."
 * November 2013 - Ueda apologizes that the game is taking so long, stating "my creative work was mostly finished a long time ago," but "the details of when, where, and how it will be completed are beyond my control."

2014

 * March 2014 - Scott Rhode states "we're not not going to announce what platform it’s coming on, who’s working on it, who’s involved. But that is still a title that’s absolutely in the mix at Worldwide Studios. That’s the most you’re gonna get.” He notes that he "loves that people are still interested in it."
 * June 2014 - IGN suggests that The Last Guardian is cancelled based on an internal meeting with a Sony Russia executive. Both Rhode and Yoshida says the rumor is wrong, that they "laughed at this rumor over dinner", and takes to twitter to say "TLG has NOT been cancelled." The Last Guardian doesn't have a showing at E3 2014. Yoshida states "It exists. The team is working hard on it. When we cancel a title and it is something we have announced already, we'll say so."

2015

 * February 2015 - The Last Guardian trademark is reissued.
 * June 2015 - The Last Guardian is revealed at E3 as a PS4 exlusive, releasing in 2016. A gameplay trailer is shown . Yoshida states that the game was changed from PS3 to PS4 because of technical concerns, and that "the announcement trailer of 2009 wasn't representative of how the game actually performed - but was "specced up" for the occasion [...] the game was running on a much lower frame rate." He stated that "there were a lot of technical issues. The game was not performing at speed. The game was running on a much lower frame rate. Some features were still missing. [...] It was clear that the team had to make a compromise in terms of features, as the PlayStation®3 hardware struggled to cope with the game's vision. [...] So it was clear that the team had to make a compromise in terms of features and number of characters so while they were taking time, the engineering team ported the code on the SPU [processors of the PS3] to improve the performance, but it was taking lots of time. [...] But, in the meantime PS4 arrived, the development environment was available. So in 2012 it became apparent we should move it to PS4 to achieve the visual [ideal.]” He stated "[the team has] a certain level of confidence about the launch window, which is why we showed it.”
 * September 2015 - The Last Guardian is shown at Tokyo Game Show with a giant animated and reactive installation of Trico.

2016

 * May 2016 - The Last Guardian is stated to appear at Tokyo Game Show 2016. A 2016 release date has been confirmed.