Players engage in turn-based battles where they command groups of mercenaries (referred to as squads) who are able to attack using weapons and magic attacks (depending on the specific combat class each unit belongs to) as well as support, defense, and healing moves. Battles involve arranging the positions of units into formations and executing action techniques.
Each unit, which includes humans and demons, has a unique set of moves to employ in combat; for example, Medics can use medicine to heal allied units, set traps, or attack enemies, while Challengers can sacrifice themselves to inflict damage over a large area. Status conditions such as confusion, blindness, or poisoning, which affect the movement and strength of units, can help tip the odds in favor of either side. Obstacles and traps can be placed onto the field itself to hinder formations, as well as flags that change how units can be directed and commanded.
When not battling, squads are represented as chess pieces, with a limited number of turns allowed per mission. If they run into an enemy piece, a battle is triggered. Alternatively, if they encounter an allied piece, they can be healed, usually for a fee. If squads encounter a roadblock like a tornado or a fierce storm, they can choose to force their way through it (and lose health), go through it slowly (and lose some turns), remove it with an item, or find another way around. During certain quests, enemy forces will deploy armaments such as cannons or catapults, which will periodically launch attacks in the middle of battles that occur within their aiming radius. These armaments can be destroyed if the squads manage to defeat the enemies guarding them.
In addition to the standard campaign mode, there are also quests assigned by different nations with specific objectives, or the player can choose a region for their units to freely move around in. Within these areas, the squads can collect resources, battle enemies, open chests to obtain rare items, take part in fights for money or prizes, and defeat "bounty" squads for rewards. If there's a contract between the squad and a nation, additional quests can be unlocked as well. If these quests are completed successfully, extra money and rewards will be distributed; alternatively, if there is a high rate of failure, then the contract may not be renewed.
Outside of quests, players will have the opportunity to travel to the capitals of the four nations, where they can purchase items, form contracts, obtain new equipment from blacksmiths, and review their war records. The Guild, which serves as a home base for all units, also offers its own merchant shop with unique items and training camps where units can learn new skills for the field, and can provide information on rival squads working for other nations.
The game supports single player and online multiplayer modes, where players can fight against other players belonging to other nations, and expand the territory of their nation via invasions. There is online cross-play support for PS4 and Vita players.
Grand Kingdom is set on the fictional continent of Resonail, where four nations are vying for dominance: Landerth, a cosmopolitan society built on commerce and manufacturing, Valkyr, a kingdom with a strong culture of warfare, Fiel, an isolated nation that acts as a refuge for those fleeing conflict, and Magion, which prides itself on its mastery of magic and magic-based technology. One hundred years after the fall of the Uldein Empire that once unified Resonail, mercenaries fight in battles throughout what remains of the region, all seeking to expand the territory of the four nations. As a rookie mercenary leader, the protagonist becomes involved in an incident which affects the whole continent, involving a legendary mercenary leader, the remnants of the Uldein imperial family, and the true history of the empire's collapse.
Development of this game was first publicly revealed within a June 2015 weekly issue of Famitsu. The game was directed by Tomohiko Deguchi, a former employee of Vanillaware who had previously worked as a system planner for 2009's Muramasa: The Demon Blade and the director of 2011's Grand Knights History, for which Grand Kingdom is considered a spiritual successor. Chizu Hashii is responsible for character designs, while the audio is composed by Basiscape.
- グラン キングダム (Guran Kingudamu)
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- Dengeki PlayStation volume 593 (July 2015 issue), page 8-9.
- Dengeki PlayStation volume 593 (July 2015 issue), page 6-7.
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- "王道ファンタジーRPG『グランキングダム』がPS4、PS Vitaで2015年発売決定！ プロモーションムービーも公開【動画あり】". Famitsu (in Japanese). June 15, 2015.
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- Romano, Sal. "Famitsu Review Scores: Issue 1410". Gematsu. Retrieved 13 September 2016.