No Terminal black magic. No broken dependencies. Just a clean interface with three buttons: , Edit , and Build .

Note: Always respect Toby Fox’s content guidelines. Mod for fun, don’t sell mods, and never distribute the original game files.

That changed with the quiet arrival of —a native, community-driven solution that finally lowered the drawbridge.

Since UMT for Mac launched, the Undertale modding scene has seen a surge of creative work from Mac users. Notable mods like Undertale: Bits & Pieces and Dusttale: Rewind were partially developed on MacBooks using this tool. The barrier has broken—and now, any Mac user with a silly idea and a bit of patience can make their own version of the Underground.