Exterminate suggests attacking and removing rival players. Since in certain games all territory is inevitably claimed, reducing a rival's presence would be the only way to attain additional expansion. extension - act of increasing in scope; making extra extensively readily available; "extension of the program to all in will need" https://l-online-l-g11086.pointblog.net/how-do-players-balance-exploration-for-dummies-86823602