West Midlands Region of the BHS have an annual inter-county Adult Mounted Games, in memory of Heather Lucas, who had been a former West Mid Chairman and pioneer of Trec in the UK.
It is great fun, the rules are modified Pony Club rules, so we creaky adults don't have to run and leap on our somewhat larger horses, but basically the rules are the same. No hitting, no whips or spurs. It is run as a team competition with riders having to pass the baton at change-over. Games were bending, ride and run on flower-pots, dressing up/tyre race, mug race and flag race. The horses soon got the idea and really seemed to enjoy it as something different and fun.
It is slightly easier on a smaller mount, but there were a few 16.00 hh taking part.
my local riding club runs adult mounted games as part of the schedule, it's great fun and one chap take in his 16hh HW cob ! no vaulting, mostly just fun games such as gallop down, walk back (so difficult on a fizzy pony!) have to turn a circle if you jog/trot. Also race to the bottom, down the cider (or apple juice for kids) and gallop back etc My sister started taking her pony in for a bit of fun ! brilliant to watch