He returned to psychiatry at age 36 when his mother fell ill. Walla worked as a draftsman, painter and photographer.
In his art, he captured his surroundings by painting invented and existing symbols as well as godlike creatures on objects (even on houses or trees).
The well-known German punk band EA80 refers to Walla's work in the piece Gugging of their 1992 album "Schauspiele".
In the fall of 2012, the Viennese label Fabrique Records released an audio book in collaboration with Peter Turrini and with selected texts and letters from Walla.
Walla featured as a character in Philipp Weiss's 2013 play Ein schöner Hase ist meistens der Einzellne.