how to install
1. have a steam copy of undertale
2. open the game files (do this by opening steam, then go to LIBRARY > UNDERTALE > SETTINGS > MANAGE > BROWSE LOCAL FILES)
3. put the data.win file of the original game in a different folder
4. put the data.win file in this folder into the files of the original game
5. open the game.
6. if you've done everything correctly, it should work, and you'll probably figure out if it works or not quickly

enjoy the chaos