The main reason 0.139u1 remains relevant is its efficiency. Modern MAME versions prioritize "accuracy" over "speed," meaning they require significant CPU power to run games that 0.139u1 can handle with ease.
MAME itself is legal—it is emulation software. However, (including the 0.139u1 list) typically involves copyrighted game code. Preservationists argue that for defunct arcade hardware, distribution of ROMs falls into a legal gray area. However, major rights holders (Nintendo, Capcom, Sega) still enforce their copyrights. mame 0.139u1 roms list