Once in Yaissor is a Windows adventure game developed by Valera Entertainment. The game features a complex storyline, well-developed characters, excellent humor, and a unique style that sets it apart from other adventure games. The game touches on various life themes and has no annoying anime characters.

Set in Yaissor during the summer of 2020, the game depicts a society where most people have become YouTubers, streamers, or other types of scammers. Nobody wants to work, and everyone considers themselves to be nihilists, atheists, and intellectuals. However, life for the common people has not changed, and those who criticize them are also part of the same society. Yaissor is no longer referred to as Europe-Asia but as Atheisto-Bydlo, with the former being led by internet personalities and the latter by Nitup, who supplies the country with essential goods. The inhabitants of Atheisto consider work to be for backward people, while Bydlo keeps the country running.