if you'd rather have the rotation performed on 1 touch
add a boolean instance variable rotating
and an instance variable OriginalAngle
on touched object > sprite set boolean rotating to true
sprite is rotating
-system compare two values - sprite.angle < sprite.OriginalAngle+90
sprite rotate towards - sprite.OriginalAngle+90
-system else
sprite set rotating to false
sprite set value OriginalAngle = sprite.angle