Ransomware
RegretLocker
According to PCrisk, RegretLocker is malicious software classified as ransomware.
RegretLocker is a Windows ransomware.
Background
PCrisk classifies RegretLocker as ransomware. On compromised systems it encrypts the victim's files and then demands payment in exchange for decryption. As it encrypts, it tacks the ".mouse" extension onto every affected file.
Source: Malpedia (Fraunhofer FKIE).