The 4,000-square-foot playground and 3,500-square-foot classroom/party area feature equipment made from recycled materials, skylights and an energy-efficient air purification system. In keeping with its planet-friendly attitude, Playgarden offers paper-free custom e-mail invites and uses eco-sensitive paper plates and napkins. Young partyers get to run through obstacle courses, zoom around on ride-on cars and animals, pedal on pint-size stationary bikes and, for a finale, “fly” in a tot-sized zipline harness. Ninety minutes of private play and party-room time gives the birthday kid and her guests access to slides, ball pits, toys, trampolines, tunnels, bridges and more, plus structured playground-style games. Pizza and bottled water are included, as is a reduced-sugar cake or cupcakes from Tribeca Treats (catering for adult guests by ’wichcraft is available for an additional fee). $1,500 for 15 kids; $3,000 for 25 kids; $25 for each additional child.