You want to play the newest protected games (e.g., Dance Dance Revolution X , Pokémon Battrio ), or you need the latest bug fixes for esoteric hardware.

Disclaimer: MAME is emulation software. ROMs are copyrighted material. Only download ROMs for games you physically own, or use the set for homebrew development.

While the ROMs (the program code) are tiny (kilobytes or megabytes), the CHDs (the game data) are massive (hundreds of megabytes to several gigabytes). Version 0.223 required CHD version 5. If you try to use a CHD from MAME 0.200 with MAME 0.223, it will fail checksum verification.