Symphogear X-Drive Unlimited is the collaboration of two major companies: Bushiroad and Gree. Bushiroad is a long time sponsor of Symphogear since season 1 and has collaborated with the series to release a line of collectible cards as part of their Weiss Schwarz brand. Gree is mobile game and social networking company involved with major titles such as GranBlue Fantasy and Idolmaster.
XDU is described as a "symphonic battle RPG" that focuses on the song and fighting elements of the series. Users can select from 9 different characters and form a team to battle against enemies while performing special moves recreated from the anime. The combat is being called a "real time auto battle" system which mainly focuses on the user inputting the commands/timing for the use of special moves.
Of course all the special moves are animated to look just how they do in the anime, including their attack names being displayed when performed. The special move used by each character is determined by what "gear card" the player has equipped to them. There are many to collect that all have different moves and abilities. The cards can also unlock additional content.
Over 100 new pieces of art were drawn exclusively for the game, including new original gear designs. The original gear designs also include their own original special moves. There are variations of each character that feature their unique gears from each season. This includes all of the gear users in the series, including characters beyond the main 6 such as Kanade, Serena and Miku. Gear cards also have an "awakened" form that will change the art they display.
Gear cards equipped to a character changes their appearance in battle. For example if you have an Ignite Hibiki card equipped then during the battle phase of the game she will appear in her Ignite outfit. Gear cards have a "spirit" level that can be raised by using them multiple times in battle. When you level up the cards you can unlock special character dialog recorded by the actors, as well as side story missions.
The main quests of the game will feature story progression through each of the 3 seasons of the anime, and more content will be added to connect with the future seasons. However, because there are some characters whose role in the story is limited (Kanade, Serena, Miku) there will also be new stories that feature them. This also includes "daily life" scenarios in addition to "battle" scenarios. There are over 100 different sub-scenarios in the game and were created under the supervision of the main writer (Kaneko).
Another type of card available to collect is "support cards." These feature characters other than the main playable 9. The support cards will have different effects and abilities that assist the player in battle. Rare support cards feature new original art that illustrate "what if" scenarios. By collecting support cards the player can unlock sub-scenarios that feature a story involving the art on the card.
All the character songs are included in the game, but have to be unlocked by completing various quests or events. Songs that the player has unlocked will go into their own "music box" and from there the player can review their various effects and parameters. Songs can be assigned to "decks" of gear/support cards the player has created. When equipped, the song will be played during battle and have different uses such as increasing attack power or likeliness of critical hits. Similar to the gear cards, by using a song in battle multiple times you can increase its level and make it stronger which leads to a bigger impact during battle.
Lastly, at the TGS event they once again had Nana and Ayahi design their own Noise for possible inclusion in the game. Nana was nervous after the birth of the "Bushi Noise" from the 2013 concert, but she was happy to find that her "Cleopatra Noise" made a better impression this time around. Ayahi decided that she wanted to see a Noise design based on a musical instrument and came up with the "piano Noise" that shoots tiny Noise out of it's keyboard mouth.
Starting in October on the XDU official site they will be starting a staff blog and manga, "Unlimi Blog" that will detail more information and progress on the game as its being made. The game is currently set for a Spring 2017 release on iOS and Android. No current word on if it will be made available overseas or not. Stay tuned for future updates!