[Nerwen]

But Belegorn and Alfirin, the question being posed is (as far as I can work out, anyway), "why didn't Gondor just go ahead and take over the entire known world?". And possibly more than that, since tom talks about "the southern continent". That, I believe, is the sense in which "treating it like a game" is meant- the OP seems to take it as a given that world domination (more-or-less) is everyone's sole objective, regardless of practicalities.