You can contact Cherry Park in Rock Hill, they have adult softball in the spring and fall. Jason Reynolds (329-5640) handles the adult softball program. They also offer adult soccer in the spring and fall.
Cherry Park (http://www.ci.rock-hill.sc.us/dynSubPageSub.aspx?deptID=9999&pLinkID=350&parentI D=13 - broken link)
I don't know what the Spring Complex offers. You can call Brown Simpson at 547-2273 he is the Director of FM Parks & Rec to find out what they offer for adults. I think Fort Mill has a flag football league.
Lots of churches sponsor adult softball teams too. Check out Roar Sports for adult sports.
Roar Sports