Soul Sacrifice Delta is a game for the Playstation Vita in the same vein as the God Eater franchise. Much like in God Eater, players engage huge monsters in battle with teams of multiple allies, either offline or online with other players. Defeated bosses drop offerings (spells which function as the game's replacement for weapons) which can be fused into other offerings to bring into battle.
A free collaborative God Eater 2 DLC exists for Soul Sacrifice Delta. It opens up the Marduk as a fightable boss, whose drops are a Weapon-type offering themed after the Marduk Short Blade and an Explosive-type offering themed after its fireball toss. Additionally, God Eater-themed costumes for both male and female players can be unlocked after fighting the Marduk in SSD enough times.
More information can be found at http://blog.us.playstation.com/2014/09/18/soul-sacrifice-delta-wield-the-power-of-the-gods-eaters/