There is so much official media relating to the How to Train Your Dragon Franchise, from games to comics, TV shows and apps. It is helpful for fans to see how these media relate to each other chronologically to form one long story. It is especially helpful for fan-fic writers or anyone who is interested.
Dreamworks Animation does not necessarily design or authorize media and keep in mind said media fitting perfectly together. However, it is possible to come up with a reasonable timeline. Because of various consistencies and inconsistencies between media, any timeline designed is up to an individual's interpretation. Below is my rendidtion. I heavily consulted with WhispertheWolf, a user on the School of Dragons Forum. I also read King of the Wilderwest's opinions on his Tumblr page.
Below is a graphic of my ideas on a comprehensive timeline, at least as of Spring 2018. If anyone is interested, I just used MS Paint to make it.
- "Racing for the Gold" - a series of video vignettes showing the HTTYD movie characters honoring the Winter Olympics. The Vikings still have an antagonistic relationship with the dragons in these videos. Hiccup still has his leg, as well.
- "Flight of the Night Fury" - a now-defunct game for iOS that states Hiccup is doing missions for Gobber and secretly riding Toothless during the cover of night. He still has his leg in the game.
- Dragon Training Legends - a suite of mini-games first released with "Gift of the Night Fury", and later on Cartoon Network during the Riders TV series. 'The Legend of the Night Fury' features a riderless, whole-tailed Night Fury saving Vikings and sheep from other maraudering dragons such as Gronckles and Terrible Terrors. The fact that dragons are attacking Berk seems to indicate this mini-game takes place before HTTYD1. Why a Night Fury is helping the Vikings is unknown. Another mini-game, 'Legend of the Deadly Nadder', shows a Deadly Nadder being ridden by a human and running various obstacle courses, indicating the Vikings and Dragons have allied, therefore taking place after HTTYD1. The other two mini-games, 'Legend of the Scauldron' and 'Legend of the Gronckle' do not have enough information and could take place at anytime. The Gronckle is running various sorts of obstacle courses on its own, while the Scauldron eats fish and avoids trash dumped by a Viking and occasionally eats them (keep in mind Scauldrons may attack a Viking ship if provoked at any time).
- "Tap Dragon Drop" - a now-defunct iOS game released in May 2012, several months before the release of "Riders of Berk". Toothless and Hiccup round up scattered sheep by burning down obstacles and roaring at them, utilizing the sheep's fear of dragons to herd them. In "Animal House", the third episode of "Riders of Berk", the Riders get the local livestock to loose their fear of dragons.
- "How to Train Your Dragon" the Game - a Nintendo game which states it takes place one year after the defeat of the Red Death in HTTYD1. This game is chock full of inconsistencies with the rest of the Franchise including but not limited to: Hiccup has both legs, there are many Night Furies, Gothi "speaks", and so on. The dragons have had advanced training in this game, so ideally it would take place after the initial "Riders of Berk" episodes dealing with dragon training. Also, HTTYD1 is thought to take place in late summer or fall because the village is preparing for the winter. Therefore HTTYD game takes place in Summer/Fall, which places it before the episode "Thawfest", which is about the holiday celebrating the end of Winter and beginning of Spring. Also to note, HTTYD game was released in 2010, well before "Riders of Berk" in 2012, so it should occur as soon as reasonably possible on the timeline.
- "Wild Skies" - a game put out by Cartoon Network to coincide with "Riders of Berk". Cartoon Network stated that they would be releasing new dragons as they appear in the TV series. The game was not updated anymore after "Riders of Berk" ended.
- "Outcast Attack" - a simple game from Cartoon Network where the player saves Terrible Terrors from the Outcasts and also battles the Screaming Death. The Screaming Death does not appear majorly until "Defenders of Berk", in which the Dragon Riders are also at odds with the Outcasts.
- "School of Dragons" Main Quests - (non-Expansion Quests) The bulk of these were released while "Defenders of Berk" was released and remain the same. At one point the NPC characters were upgraded to their older look in HTTYD2 from the look of HTTYD1, but Stoick and other things remained the same. Then version 2.0 was released in June 2016 and Stoick was removed from the game, updating the game time line to after HTTYD2. Valka and Eret were added, and Quests Stoick was involved in were divvied up to other NPCs. Later still, SOD introduced a new starting Quest, where the new player fights against Dragon Hunters and frees a captive dragon. The Main Quests were essentially updated to a post HTTYD2 timeline. So, depending when the player started playing, the original Quests may be thought of as pre or post HTTYD2. Main Quests released after version 2.0, however, would only be considered post HTTYD2. These include: Carpet Seedling, Shrinking Sheep, Pin Cone Weather Station, Paint Up a Storm, What a Mess!, Scrubbed Clean Parts 1 and 2, Gobber's Wheels of Misfortune, Honey I Shrunk Snotlout, A Slick Solution, Back in the Saddle Again Parts 1 and 2, Rumbling Docks and Sundial Clocks, among others.
- "School of Dragons": Icestorm Island Expansion - This first expansion for the game was released a few months ahead of the release of the first season of "Race to the Edge". It contains Mildew who last appeared in "Defenders of Berk", Stoick was still an NPC in the game, there are no elements from RttE, and the Hooligans and Berserkers were still hostile with each other.
- "School of Dragons": Call of the Deathsong - This expansion was released in August 2015, a couple months after the release of the first season of RttE. The Deathsong and Razorwhip appear in the Season and Expansion, as well as Heather as the "Rogue Dragon Rider" in the episode "Have Dragon Will Travel, Part 1". Heather's discovery is different in the game because she is already used as the School's Alchemist.
- "School of Dragons": Battle for the Edge - This expansion was released ahead of RttE, Season 2, and is stated to be inspired by the Season. It had to take place, at a minimum, after episode 3, "Night of the Hunters, Part 2" as this two-part episode was when the Dragon Hunters were introduced to the Franchise. Later, in the episodes, "Edge of Disaster, Parts 1 & 2", Dragon's Edge is attacked.
- "To Berk and Beyond" - This is a companion book for the Franchise with collected information and small stories from the characters. In the forward, Hiccup indicates this is a 'scrapbook' he started when he and Toothless met (HTTYD1). However, nearly all imagery is from the HTTYD2 era. The book itself was published in 2015. There is a sense of the passage of time, starting with an entry from Stoick, and progressing to later entries from Valka and another of the Riders describing what they did to distract Drago's Bewilderbeast. An early entry also mentions Dragon's Edge as a newly discovered island.
- "The Eel Plague" Mini-Comic - This takes place when the Riders are fully entrenched at Dragon's Edge, and have the original Dragon Eye in their possession. Hiccup takes it along on practice maneuvers so it won't be left alone on base. So this needs to take place during Seasons 2-3, possibly partway through 4.
- Dreamworks Press: Dragons: Book One: "Flight of the Returnwing" - a lovely interactive book app that was never completed. In it, the reader becomes a stranded viking who has forgotten their memory and is saved by the Riders. Berk's Dragon Hangar is built, placing it after RttE (as well as the release date). Dreamworks states it takes place before HTTYD2.
- "To Tame a Titan!" - This is an eBook of sorts published on Dreamworks' Official Facebook page. It features several artwork images with captions that make up a story. The first picture caption indicates it takes place at the same time as the Dreamworks Press: "Flight of the Returnwing" interactive book app.
- "Dragons: Rise of Berk" Quests - This game has a long sequence of Quests to complete. They function more as goals or milestones to reach. The Dragon Hanger has been built in the game and Stoick is still alive during the beginning quests. However, as the Quests progress, Stoick dies and the Quests continue on in a post-HTTYD2 scenario.
- "Dragon Racers: Dragon Berry Dash" - This small game was released in conjunction with Bazooka Candy Brand to promote the launch of HTTYD2 in 2014. It is no longer available. The player plays Hiccup flying on Toothless through several levels of courses to save an 'Alpha Dragon' (a Bewilderbeast) from 'Evil Forces'. Hiccup wears an outfit most similar to his flightsuit in HTTYD2. It includes the red insignia on his shoulder. This indicates the game takes place around the time of HTTYD2, when Hiccup's outfit changed (shortly before the movie takes place). The otherwise vagueness of 'evil forces' and the presence of a Bewilderbeast can further place it anytime through or after HTTYD2. Potentially it could take place after Season 6 of RttE, except Hiccup's suit is more aligned with that of HTTYD2.
- "How to Train Your Dragon 2" the Game - This is another Nintendo game. Gameplay involves completing goals such as chasing other Dragon Riders, completing flying challenges, and visiting certain check points around the Isle of Berk. Stoick appears, but so does Valka, albeit masked. This could place the game before Stoick's death and while Valka's identity has yet to be revealed.
- "School of Dragons" Return to Dragon Island Expansion - The release of this Expansion marked a major change in the game. It removed Stoick from the game and added Valka and Eret. All main quests involving Stoick were given to other NPC characters. This marked the shift of the "School of Dragons" timeline from before HTTYD2 to after HTTD2. The Expansion itself involved Hiccup 'returning' to Dragon Island (where the Red Death was defeated in HTTYD1). Because Stoick was now deceased for this Expansion, and the fact that the following Expansion coincided with the events of "The Serpent's Heir", this Expansion could tentatively be placed during the final scenes of HTTYD2. There is an undetermined lapse of time between the scene showing Drago's defeat on Berk, and the final scene showing the Hooligans trying to return to normalcy and Dragon Racing again.
- "The Serpent's Heir" - This graphic novel takes place shortly after the ending of HTTYD2, and Hiccup must start the hard work of leading his people and also cleaning up the village.
- "School of Dragons": Secret of the Leviathan Expansion - This Expansion has a brief dialogue from Hiccup in the beginning, who does not feature prominently in it. Hiccup indicates he has to take care of an emissary from Nepenthe, a direct nod to the events in "The Serpent's Heir".
- "School of Dragons": Rise of Stormheart and Wrath of Stormheart Expansions - These two game expansions happen sequentially after HTTYD2 and the Secret of the Leviathan Expansion. Rise of Stormheart is first, followed by Wrath of Stormheart. It involves a game-exclusive villain named Nikora Stormheart.
- "Burning Midnight" - This is a comic directly tied to the upcoming "Dragonvine" graphic novel.