Back when I first discovered that you could run a build of Undertale on iOS with the correct Gamemaker Studio runtime, I set out to learn how I could make a full port of the game to mobile platforms.

​I taught myself GML to modify the game using UndertaleModTool as well as C# to script my changes. The port uses simple on-screen controls to emulate controller input.

• Touch screen controls which emulate controller input

• In-game text adjusted for mobile where necessary

• Virtual keyboard pop-ups where keyboard input is required

• Expanded settings menu to include on-screen control options

• Game scaling adjusted to support a diverse set of mobile device resolutions 

• Changed an easter egg to be activated by shaking the device instead of by keyboard input