things luxembourg invented
Gaelic Sports Club Luxembourg was created in 1978.
New Zealand is well represented on the international scene in both Rowing and Cycling, so had the ball not been invented it is conceivable they would be national sports. Other sports that could be considered are: Yachting Swimming Athletics Surfing
I would die if sports wasn't invented
Tennis is said to have been invented there in the 19th century, though there were variations of racquet sports already in existence.