Squash 57

If that doesn't ring a bell, this squash game used to be known as "racketball" or "racquetball". Wikipedia knows more about it: Racquetball@Wikipedia

Squash 57 with video and info on the Swiss Squash website (German or French)

Most of the game forms and exercises on squashtraining.ch can also be played with the Squash 57 material and are marked accordingly in the filler selection.