The MSG file extension is used by Fallout 1 and 2. Fallout is post-apocalyptic open world video game. MSG file contains game character, dialogues and messages.
The MSG file extension is commonly used for Microsoft Outlook. A *.msg file can either contain only text, or complete saved message with pictures and other elements in HTML format. MSG file contains multiple e-mail fields, including the date, sender, recipient, subject, and message body.