My natural inclination leads me to Athene – and at the very least she’d be in charge of wargames.
(There is a Greek d20 in the British Museum.)
Saints are trickier. Balthasar or Cajetan, I guess. https://weirdcatholic.com/2018/07/12/the-patron-saint-of-gamers/ has more.
For solo gamers, I nominate Theoktiste of Lesbos (“At the island of Paros, she was able to escape her captors, and lived in solitude there for 35 years, until she was found by a hunter (sometime in the 870s).”) (And let’s face it there aren’t enough Lesbian saints.)

