o2em is an emulator for the Magnavox Odyssey II and VideoPac+ systems. The Odyssey2 BIOS ROM image is required for emulation. To include it in the package, get either the odyssey2.zip used with MESS, or else the ROM image itself, called either o2rom.bin or o2bios.rom, and place it in the build directory before running the SlackBuild. The ROM will be installed in /usr/share/o2em/bios/o2rom.bin; if you build the package without the ROM, just place a copy of the ROM there after installing the package.