Worlds Collide is an event update that linked Dragon Saga and Ragnarok Online, another mmorpg from the same developer Gravity Interactive.
Crossover content included new quests, quest rewards, costumes and dungeons. WarpPortals were opened up to connect the two games.
In terms of story, Worlds Collide introduces the Kafra employee, Telling, who travels from Ragnarok Online to Dragon Saga to seek help in saving her home town of Geffen.
Ragnarok-themed pets and mounts could also be obtained from treasure boxes that drop from the newly added maps.