Before google updated their servers you could just copy & paste the game link in the google
playstore web into a web page that downloaded the apk for you, Then you put the apk in your
sd card and installed whatever app you downloaded.
It only worked whit free apps for obvious reasons, But single google did "something" that is
no longer possible. For region locked games like japanese apps, You could just use Qooapp
but if you mean normal apps like widgets, tools or such then you're out of luck...
Unless you have a friend whose phone is compatible and have him share the apk with you.