Undertale v1.00 Undertale v1.00 Undertale v1.00 was the first complete version of UNDERTALE that was released on September 15, 2015. Undertale v1.001 For images showing the changes, see here. Toby Fox first announced Undertale v1.001 on January 12, 2016.[1] Beta testing for Undertale v1.001 began on January 19, 2016, and was only available for those with the Steam version of Undertale.[2] This version of Undertale was later deemed official on January 20, 2016[3], and was later made available for those who bought the DRM-free version of Undertale on January 21, 2016