oneWheat is the name under which a developer in Tokai, Aichi Prefecture, Japan makes apps alone in evenings and at weekends, according to the official site and the developer's note post. The App Store seller of ソリティア世界旅行 is Shunichi Kondo. The developer writes on note as shun and on Zenn as shunchobi, and says they first made a solitaire app about ten years earlier while studying in Canada.
Klondike solitaire as a trip through 34 watercolour cities in Japan and Korea: clear a game to earn coins, buy a plane ticket and fly to the next city. The solo developer says Claude Code wrote the code.