Probably safest to run it in an emulator with no internet access, given where it was found.

APKs are signed so assuming OP can verify his own certificate he might be lucky enough to not have to dig that deep.

	▲	diggan 28 minutes ago \| parent [-]
		If it's being distributed by a piracy site, and the game had any sort of protection to make sure people actually bought it, then probably they're storing/offering a pre-cracked version, which certainly shouldn't (or wouldn't) be signed by anyone.