BIOHAZARD A.T.N. ASSAULT THE NIGHTMARE is a video game in the Resident Evil franchise. It was released in 2002 for NTT DoCoMo's 504 and 505 phones in Japan. It was sold as part of a subscription to 'Capcom Party' at ¥350 per month. Later, the game was adapted for western mobile phones as well. Following talks with European phone operators, Capcom released the game internationally in mid-2004 under the title, "Resident Evil Assault the Nightmare".

The game takes place at an isolated mansion on the hills, which is sometimes refereed to as a castle depending on the version of the game. The player controls a police officer who was sent to investigate after the local police precinct received an emergency call (or "SOS signal" in some versions) from there.

After searching around the mansion, the player character is able to unlock a corridor where a licker is fought as the final boss. After defeating the licker, there are four possible endings with the protagonist rescuing a survivor of the incident. The survivor can be a dog, an adult man, a crying woman, or a pair of children.

The game location presumably is a nod to the Arklay mansion, and the player character apparently is a representation of Chris Redfield.