Wiktionary
n. {{context|idiomatic|almost always preceded by (term: the)|lang=en}} The only opportunity, activity, or resource available.
Wikipedia
Only Game in Town is an album by New Zealand band, The Warratahs released in 1992.
Usage examples of "only game in town".
You'd have thought young bucks would have been clustered around Kit like high rollers around the only game in town, but I had her to myself.
But we're the only game in town that's working toward restoring this nation.
He realized that all of the odds were long, but knew that the gamble would be worth it because it was the only game in town and he was no longer content to just wait for death.
As warships, they were nowhere near the class of an Enterprise-model starship, but, for now, they were the only game in town.
Or maybe it's just that this is the only game in town right now, and when it's over, it's gonna be boring as hell.