Translation:They play together everywhere in Europe.
I get denied "They play together all through europe" ? all through, through out, all over, everywhere are ALL valid translations for partout!
Duolingo probably should allow that, although I think "(tout) autour" might be more precise for your English phrase.
Here's a link to a translation of Louis Attaque's "Du Monde Tout Autour" ("People All Around"): http://lyricstranslate.com/en/du-monde-tout-autour-people-all-around.html
A fun way to get the phrase in your head!
Reverso says throughout can be partout, but the sentences examples are for when it means everywhere. Like there is carpet throughout the house.
It gives throughout in the sense of throughout a country as dans tout(e) le/la
So Ils jouent ensemble dans toute l'Europe - Europe is feminine as you prob know :)