Only Game In Town Meaning

(idiomatic, almost always preceded by the) The only opportunity, activity, or resource available.

Example: 1973, Stanley Elkin, Searches & Seizures: Three Novellas, ISBN 9780879232535, p. 265 (Google preview):
  It was the first elected position he had ever held, his single incumbency and, he had to admit, his best prospect, the only game in town.
1995 Nov. 12, Adam Rogers, "Now For Some Hotjava," Newsweek (retrieved 1 Jan 2014):
  Java won't long be the only game in town. Microsoft already plans to publish a rival software, code-named Blackbird.
1999 Dec. 12, "Will The Yen's Surge Do Japan In?," Businessweek (retrieved 1 Jan 2014):
  When exports are the only game in town, currency gyrations can be a killer.
2013 Oct. 24, Adewale Maja-Pearce, "Nigeria’s Talking Shop," New York Times (retrieved 1 Jan 2014):
  Political power, after all, is the only game in town that ensures unfettered access to the nation's oil riches.