Kantai Collection (otherwise known as KanColle) is a web/mobile game made by Kadokawa/C2 and published by DMM. (For those of you who have played Touken Ranbu, the two games play and look very similar.) In the game, you are a commanding officer of a naval base, where your ships are shipgirls, who are embodiments of historical ships from the World War II era.
The designs of these shipgirls lend well to push the limits of my sewing and crafting skills, and the costumes I make from this series are the only ones where I combine sewing, props, and armor in one costume.
Costumes made from this series: