: Like many arcade games, Metal Slug 6 requires corresponding BIOS files (often awbios.zip for Atomiswave) to be present in the same directory as the game ROM.
Metal Slug 6 MAME 0.139u1 (MAME 2010) ROM set, you need to ensure both the main game file and the necessary system BIOS files are present in your ROMs folder. Core Compatibility The ROM set is specifically designed for the metal slug 6 mame 0.139u1 rom