I just saw this on living social and it's a good deal considering tickets are $27 bucks online. I've been in the summer and tickets are $32 so for $15 it's great, even with all the extra stuff.
From website:
Take the fun to new heights with a day out for the entire family at April Holiday Carnivale @ Xscape at the City! With rides, food, entertainment and more, there's something to keep everyone happy.
The kids will go wild with adrenalin-pumping rides like The Drop and Runaway Train Rollercoaster, not to mention the dodgem cars and the giant trampolines. Your little ones can have a play in the KidZone Under 5 area and take a smoother ride in the Taxi Jets. And with the Junkadelic Brass Band playing and Zap Fire Spectacular on show plus free parking, we'd say you adults will also be getting in on all the fun. Now that's school holidays done right!
Website: http://www.xscapeatthecity.com.au
Been there. Done that. Loved it. :D