“Runic” here refers to a made up “language” (really just a trivial cipher) that vaguely resembles Nordic runes. It’s a common thing across many video games, starting with RPGs in the 1980s such as the Ultima series (which itself took them from paper RPGs). It’s a basic 1:1 mapping of some runes that nerds like onto English letters. For some reason this same mapping has persisted across many games over many decades.
Of course nobody ever acknowledges the white supremacist subtext of ignorant nerds choosing some imagined “Viking” runes for this because they’re “cool” or “historic” or “mysterious” or whatever.
