Compression support! Since RetroArch can run games directly from archives it's possible now to compress non-NES games using 7-Zip. This feature enabled by default but you can disable it in the settings menu. Also you can add the whole archive (required by MAME games).
Maybe @Cluster or anyone else can answer...is this saying that it will automatically compress any ROM files automatically and then load them? If I already had each ROM in its own 7z file before I add them to Hakchi2, haven't I already done the same thing? Just making sure I am not misunderstanding. Thanks.