Kami wa Game ni Ueteiru.

Bored gods create complex games to entertain themselves, using humans as their opponents. Selected individuals known as apostles compete against them in these mental challenges on a spiritual battlefield. Leoleshea, a former god who has awoken after millennia of sleep, seeks out the best player of the current era. She meets Fay, a promising new apostle. They intend to take on the gods and claim the highest reward, though no human has ever completed ten games. The challenges are unpredictable and often illogical, leaving apostles with little choice but to embrace the bizarre nature of the contest.