A visual novel by Nitroplus and 5pb for the PC. It was later ported to the Xbox 360, PSP, and iOS devices. It's about a shut-in high school student that gets involved in a murder case and must cope with that and the errant delusions he faces.
A visual novel game released in 2002 that focuses on a group of people who are trapped in an undersea theme park. Mysterious happenings are abound and time is running out so the group must band together to escape alive.
Absolutely horrifying game and a nod to Lovecraftian horror. Wish more similar games came out.