In DM could mean something different because there's no cooperation on that game type. For example, I only type GG at the end when the opponent or opponents were really good, no matter if I won or not.
Totally agree with Bigboss. It's impossible to determine why people type GG because that depends on each player personality and mood at that time. They could be honest or sarcastic, or maybe they just type it by costume, they don't even think if they should do it or not. As you said, for you "gg" is a congratulatory remark, but maybe it's not the same for them. If you really wanna know, you should ask them.I guess the meaning is really relative though to the type of player you are and your sportsmanship. The whole who does it first thing? i think that is just whoever can remember first, and whoever can type the fastest
