I remember playing some gamemode back in Gmod 12 where basically you'd have to control different zones on this one map. There was a treehouse, cave, warehouse, house, etc that you would control and collect points. I forgot if it was team based or if you went solo but basically you could level up and after the round was over, you'd go to a lobby type area where you could purchase new guns and whatnot. When I played, there was only one map. I also remember how the high leveled players would basically destroy you. There were custom models and it was a neat game but I completely forgot what it was called.