GG:

GG means “good game,” a short chat message used in Dota 2 to signal acknowledgment of the match’s outcome. It is often typed at the end of a game to show sportsmanship, and in some cases a team may use it to indicate surrender or concede pressure, especially in organized play or custom agreements.

In Dota 2 chat, GG is one of the most common end-of-match phrases and is also used in combinations such as “GGWP” (“good game, well played”).