If I were to win the lottery, I'd buy a locally-popular golf course and immediately convert the club house into a soup kitchen and no-pay community space, and let the grounds mostly return to nature. Maybe do a lot of tree planting. I'd keep some nice walking paths and a few big clearings for events like modest-size music festivals or just general casual park stuff. And some skateparks. And I'd put in multiple new mini-golf courses within eyeshot of as many surrounding houses as I can because I love mini-golf.

Longer term, I'd settle in for the legal fights from supremely pissed-off people in the surrounding community because they would be bound to be epic.

Update: oh, and basketball courts! Can't believe I forgot those.