Could you do a flag version of rugby?
Like NFL it's more than a contact sport - it's a 'collision' sport.
Contact with head is strictly against the rules, but the nature of the games makes some impacts to the melon inevitable - most likely from hitting the turf hard.
The codes have introduced concussion protocols, but it's a professional sport. Rule bending to advantage is part of the caper.
There are flag versions and non contact variants already, but they are small time fitness sports compared to the pro leagues and unions.