There are quite a few small parks dotted about.
There is also a water park called Aqua Water Park in Didim, see this link for more details
Didim Aquapark NASIL Gidilir - How to get there ?
If your child likes Go Karting there is also a new Karting track in Mahevesir, its not too big but has enough twists in it for kids (and grown ups!) to enjoy.
Hi, Where in mahevesir is it ? and how much does it cost