Gurumin: A Monstrous Adventure is an action-adventure game developed by Nihon Falcom for PC on December 24, 2004 and was later released for the PlayStation Portable in 2006. Mastiff eventually published Gurumin in the United States on the PSP in 2007 as well as the PC in 2015 and finally the Nintendo 3DS in 2016 with a new port created by Mastiff.
A girl named Parin is sent to live with her grandfather Hyperbolic when her parents set out on an excavation. Parin stumbles across another child in Tiese Town after being told there were no other children in town. This child is being attacked by a dog and is then saved by Parin.
After saving the other little girl, Parin finds out that this girl is not a human, but a monster. Only kids can see these monsters and villagers in Tiese Town think she is talking to herself.
After saving the monster named Pino, Parin is then introduced to her brother Puku. Puku decides to let Parin visit their home of the Monster Village. Monster Village is attacked by phantoms while Parin is in the Potato Ruins and she must help the inhabitants rebuild.
- Gurumin was the first fully 3D game to be developed by Nihon Falcom and its graphics engine would live on at the company for a very long time. During a 2020 interview with Gamer, Toshihiro Kondo revealed that the company's current 3D engine originated from Gurumin which they had been updating and modifying for years. While not all of the company's games used this technology, with some titles instead using Sony's PhyreEngine, Falcom had basically been creating games with a version of Gurumin's engine for over 15 years before finally creating a new engine, which debuted with Kuro no Kiseki in 2021.