When he realised his passions lay with drawing, he enrolled in Technology school and passed with good qualifications.

[3] Inspired by the early comic artists from the United States and England in the late 19th century, Andersson created Sweden's first recurring comic strips: Bröderna Napoleon och Bartholomeus Lunds från Grönköping Resa Jorden Runt (about two brothers on a world tour), Mannen Som Gör Vad Som Faller Honom In (about a strange man who does whatever comes to his mind) and Urhunden (about a prehistoric dog and its owner), all around the turn of the century.

[2] In 1906, Oskar, who apparently experienced long depressions and obsessive-compulsive disorder, committed suicide by shooting himself.

[citation needed] The reasons for this are not entirely known, but Andersson was also known for his social anxiety, as well as incidents during his work as a reportage cartoonist, as he was exposed to severe mistreatment of military horses, which as an animal lover worsened his depression.

Among his contemporaries, Andersson was primarily known for his caricatures, which were published in Swedish newspapers Söndags-Nisse and Strix, between 1897–1906.