Er0rr?Sans Fight - Underdifficulty

This is a Undertale Fangame for the AU (Alternate Universe) Underdifficulty.

Underdifficulty is an AU where enemies get way harder, and everyone is error-ified. Sans is only extra Error because Error Sans already exists.

To open in Mac, open Finder > Navigate to the application > Right click > Open > Open.

Type start.sh for Linux.