"This fortress is our home. We will not let the enemy shatter it." — Captain Phoebe of the Crystal Guard You take control of Phoebe - fierce warrior, skilled archer, resourceful engineer and fearless commander of the Crystal Guard. Summon powerful soldiers and snipers, mount defensive turrets on the battlefield and get to the frontlines — whatever it takes to leave the fortress intact. Action point-based tactical gameplay Units recover a limited number of action points (APs) per turn, requiring careful planning. Should you act aggressively with your current points to approach and attack the enemy, or stay put and defend to recover additional points while letting them get closer to the fortress? But beware: enemy units can act the same way! Fast-paced turns In this game, you only control the main character. After you make your move with Phoebe, all ally units take their action simultaneously, followed by all enemy units at once, resulting in a very fluid and quick passage of turns! Upgrade system for all units Spend your gold between battles to power-up each of your units, increasing their Max HP, Max AP and AP Recovery, Damage, among others. Be prepared, for the enemy waves will grow relentlessly. Chapter-based stages Experience stage progression divided into chapters, providing different environments to play as the Crystal Guard shifts their defensive efforts to each of the four gates.