In Game Tile Editor for UnderTale and DeltaRune
The tile editor, inspired by Agentalex9’s unreleased work, is available to try for beta testing. Please read "HowToUse.txt" and "README.txt" before using the tool. Further information is provided in the "Documentation" folder if needed.
You will need to select which version of GameMaker your game is based on. For Undertale on PC, use the GMS1 version. For Deltarune or Undertale on Switch, use the GMS2 version.
UPDATE: Borders are now forced off in order to prevent unexpected behavior.