Final Fantasy Record Keeper

 is a free-to-play role-playing gacha game developed and published by DeNA for iOS and Android. The game features original characters and stories interacting with characters, scenarios, and battles from other games in the "Final Fantasy" series. It was released in Japan on September 24, 2014, and worldwide on March 26, 2015. The gameplay primarily consists of Active Time Battles with 2D sprite graphics. It has reached over 10 million downloads worldwide and is available in Japanese, English, French and Spanish.
Gameplay.
Players enter each "Final Fantasy" titles world and fight to clear dungeons. As they accomplish this, they unlock new characters from those games. Players can combine parties of characters from different "Final Fantasy" titles. However, though using a game mechanic called "Synergy System", playing the characters that are initially from the world you are in gives characters a "stat bonus". This also applies to weapons and gear. The game has players reenact many moments from the "Final Fantasy" series, such as the Battle on the Big Bridge against Gilgamesh. Characters can be given weapons or abilities that are collected along the way. The game is free-to-play but does have microtransactions.
Plot.
Players control Deci, a researcher who works in the history department for Dr Mog. Being his best student, Dr Mog shares his magic so that Deci can enter paintings and see memories of different worlds, which are previous "Final Fantasy" titles.
Development.
Developer DeNA proposed doing a social role-playing game to Square Enix that would center around the "Final Fantasy" series, similar to a title the developer had worked on previously called "Defender of Texel". That game used pixel graphics and characters battling in formation. Square Enix producer Ichiro Hazama decided that DeNA had the experience to build a successful mobile game for western markets and gave the game approval to be developed. Square Enix oversaw the game and the story, setting, and characters, but DeNA completed the backend publishing. DeNa producer Yu Sasaki stated that international release was expected to happen upon initial launch of the game but was delayed and released after modifications were made to please western audiences.
For the international release of the game, artwork from any remakes that had been done of earlier "Final Fantasy" games were used, as developers felt that American audiences connected more to later "Final Fantasy" games than earlier ones. Cutscenes were looked at again and polished for the same reason. The game was designed not to be difficult, and character profiles were also added for international release so new players could easily start enjoying the game. Tetsuya Nomura designed player character Tyro and supporting cast members Dr Mog, Cid, and Elarra. To draw in American audiences, the first world entered in the game is from "Final Fantasy VII", and the next two are fan favorites in Japan: "Final Fantasy IV" and "Final Fantasy VI". When the game runs events, characters are chosen based on player popularity. Characters are not added from games if there are not enough worlds or events from those same games. The game's producers felt that characters should be winnable through battle, and the game's currency of mithril given generously to encourage players to keep playing. Enemy bosses are animated, in a departure from the style of the older titles that are being referenced. Activities such as logging in to the game earn players in-game currency, and more opportunities to obtain free game currency were added for the international release. Western and Japanese versions of the game are on different servers, so no player communication is possible between the two versions. Producer Ichiro Hazama stated that the core of the experience of the game is “reliving the past”. Hazama also felt there was room for original story expansion in the game's plot and the new main character Tyro. On July 15, 2014, a teaser site appeared with a timer counting time for the game's actual reveal.
Reception.
"IGN" praised the game's use of nostalgia for previous "Final Fantasy" games and fun combat and customization. However, they criticized its lack of character interaction and shallow story, making it hard for the game to hold players' interest. "Kotaku" voiced a similar sentiment, calling the game a "fun time waster" but noting the presence of the "much loathed stamina scheme" used to entice players to pay for more play time. "VentureBeat" said that the crafting and combining of items and weapons was "actually fun" and felt like a real "Final Fantasy" game, but condemned the gameplay as being boring because it is primarily a "hands-off" experience.
Within ten days of release, the game was downloaded over one million times. After a month, the game recorded three million downloads and one billion yen. The game reached five million downloads in six months in Japan and was in the top five highest-grossing games in the Apple App Store.