Translation guide
A hybrid game combining elements of football (soccer) and rounders, played mainly in UK schools. The Japanese equivalent is a direct loanword, but the concept is not widely known.
Referring to the hybrid sport football rounders
Direct loanword from English. Used in contexts where the game is known, such as among PE teachers or in international schools.
We played football rounders in PE class.
Since the game is not widely known in Japan, you may need to explain it as a mix of football and rounders.
It's a game that combines soccer and rounders.