My mom's horse LOVES to game. If he sees a barrel or pole in the arena he gets all dancy and just can't wait to get running around it. When we show he will do the performance classes but you can just see him waiting until the end where he can run as fast as he can, spin around those barrels or weave around the poles.
My horse on the other hand just loves to be ridden, period. He loves to go on trail rides, he loves to game, and he love doing performance classes like trail, horsemanship, and western pleasure. When we get into the trail ring (competative trail) you can just see him thinking about what his next move is going to be. In horsemanship he loves to do the best he can, if I ask him for the pattern he just perks right up, settles into that nice western performance frame. And it's the same for the western pleasure. He just turns right on. But the funny thing with him is, if I ask him to game he starts doing the little dance waiting for the gate to open (I think he learned that from my mom's horse lol) and let him in so he can run it, then when he is done he goes back to his spot, falls asleep, and waits for the next thing on the list :)
With my horse I will know when it's been to much because he will stop coming to the gate for me. We showed yesterday, it was crazy hot, he had to work a lot (3 performance classes and 1 game). This morning when I went out to get him so we could do some work he ran right up to the gate (he is in a HUGE grass field which he just went into for the summer). He was on the other side of the field when I got to the gate, and he still ran to see me.