[Mahou]

I don't really think there is an age cap unless you're physically unable to play. There are a few ITG machines in my area, but the game doesn't really interests me the same way as it once did in my late teenage years.
Also, the ITG community in my area is pretty nonexistent because new things have came out. A lot of the rhythm gamers I'm friends with like to play iidx, piu, osu standard, etc. The ones I know of who still play have their own private machine. Personally, I'm probably never going to contact those people because I find the idea of strictly wanting to visit someone's house just to play a arrow smashing game kind of awkward.