Board Thread:General Discussion v2.0/@comment-27234286-20151118175310/@comment-27036118-20151128044720

Toby confirmed in a tweet that if he makes a patch, people should expect anything other than bugfixes. Undertale is such a complete game, and while there are areas where things could be extended, such as Hard Mode, I think that's there's not much more Toby can/will do with Undertale.