1 : suggestive of an uncle especially in kindliness or geniality avuncular indulgence 2 : of or relating to an uncle
1 : >Jovial and avuncular, the President’s chief of staff seems oblivious to the pressures that accompany what is arguably the second most powerful job in the land. —Craig Unger
2 : >Two weeks of poker had led to his writing to his uncle a distressed, but confident, request for more funds; and the avuncular foot had come down with a joyous bang. —P. G. Wodehouse
I did some digging incase the definition wasn’t representive of something for gaming. I didn’t see anything beyond the fact that definition two can also pertain to physical features. So I think this one’s on here for reading references, and perhaps usage in describing the personality or physical traits of an NPC. An avuncular person is non-threatening, either in appearence or mannerisms.