According to the game's official Twitter account, the developers claimed that the only characters they would not add to the game if they became, or were discovered to secretly be, public domain were Calvin and Hobbes from the comic strip of the same name. While the characters are still copyrighted thereby ruling them out, the reasoning for refusing to consider them was out of respect for creator Bill Watterson and his refusal to license the comics for merchandise despite their popularity, feeling that it would go against the strip's ideals and ruin its authenticity.