WTA = Winner Takes All as opposed to PPSC = Points Per Supply Center.
in WTA games, if someone gets 18+ SCs, they receive the entire pot, and all the losers get no points (this is a closer approximation to the board game, i believe, as there are no points involved there). in PPSC games, if someone gets 18+ points they get half the pot and surviving players get a number of points per supply center ([pot/34]xSCs). a draw divides the pot evenly between players in both WTA and PPSC. you have to have more than 100

to start a WTA game, but not to join one.
TMG - the master gamer, as opposed to TGM - the ghost maker, they are two players on this site who together created the Masters Tournament that is currently starting.