If you are trying to open a data1.arc file yourself, standard programs like WinZip usually won't work. You’ll likely need a community-made tool specifically designed for that game’s engine, such as ARC Tool or Fluffy Manager .

Modders often use specialized tools to "unpack" these archives. Once inside, they can swap a character’s costume or change the game’s music by replacing files and "repacking" the archive.

Many .arc files use compression algorithms to reduce the game's total footprint on your storage.