.hack//Infection is the first installment in the .hack video game series developed for the PlayStation 2. Set within a fictional MMORPG called 'The World', players follow the protagonist as they investigate mysterious events that occur both in-game and in the real world. The game combines RPG elements with a unique narrative style, blending offline adventure with online simulation. It is the starting point for the .hack//IMOQ (Infection, Mutation, Outbreak, Quarantine) saga.