Girls' Frontline is a moe anthropomorphism game in which the player controls echelons of android characters, known in-game as "T-Dolls" or "Tactical Dolls", each of which represents a real-world firearm.
The player plays as a newly recruited commander of an area who commands the T-Dolls in battle, and organises the echelons as well as the T-Dolls' wellbeing. Battles are a mix of turn-based strategy puzzles on a set map with enemies that can move about, random item nodes and heliports/command nodes, from which the player can summon their own echelons, or support echelons, which are echelons that the player's friend sets on their profile to be used by others, and real-time battles with enemy echelons. Battles are for the most part automated, although the player can activate the T-Dolls' special abilities manually if wanted, or order them to different spots in formation (which the player can organise out of battle to be set as the default formation when entering a battle) or to withdraw in order to conserve health or resources). Players also have the option of withdrawing specific echelons from the mission altogether if they wish. Gameplay progresses by playing on the campaign missions, logistic support missions, or combat simulations to level up each T-Doll. The game also features gacha elements, such as in the production and heavy production of T-Dolls and equipment, or in the Dormitory with costumes and furniture sets for the T-Dolls on a time-limited basis with several sets and costumes being available for a limited time, before another few sets and costumes are revealed and added. After a while, old costumes from previous gacha events will be added to the "Black Card" store, where players can exchange an amount of Black Cards (obtained from gifting T-Dolls a duplicate costume that has already been gifted before) for a costume of a previous gacha set. Players can customise their dorms with furniture, and interact with Chibi renditions of the T-Dolls in the echelon corresponding with that dorm. They can also gift the T-Dolls food and costume, which raises the affection of the T-Dolls. Affection is also gained from success in battle, and is lost when the T-Dolls die (unless it is a boss battle) or when another T-Doll in the same echelon dies.