The game takes place in a world where mech combat has become a dominant force, and players must navigate this environment to progress through the story. The gameplay focuses on battling against enemies and customizing their mechs, known as TS units.
Battles in Faselei are a mix of turn-based and real-time elements. The player first selects actions at the start of each turn, with the number of actions available depending on the type of TS unit being used. Once this initial selection is made, everything plays out in real-time for the remainder of the turn.