Hi! I really like this game and I want to port it to the Vita, along with King of Machines. Is that okay with you? (no need for source code or anything btw)
It's a combination of UMT (Undertale Mod Tool) and some experimental scripts that downgrades the bytecode from 17 (GMS 2) to 16 (compatible with Vita runner), and modifying code by doing some sort of decompilations. Sometimes it's a lot of work, but in the case of King of Machines, it was the easiest port I've done in my life. That game is so well coded that it literally worked right away and I had to modify nothing.
Last night I tried to port Warlord and there were some bugs with fonts that I'll look into to these days!
If you want to know more, send me a dm to @m1s3ry_