If it's raining and you're in the Kittybrewster area, you could do a lot worse than to pop in here with your small kids! It's a little run down, but it's currently undergoing the slow process of getting done up and it's always kept clean. The staff are friendly and after you've been once or twice they'll have remembered your children's names and will make them feel special.
Small toddler area for the under twos and a larger area for the older kids. I'd say once kids are over the age of 6 or 7 they'd be a bit bored with the place, but it's great for pre-schoolers and early school year age kids who can run around safely and burn off extra energy while the parents sit and have a cuppa!
There's a nice little cafe area which serves hot and cold drinks and foods (the chilli is pretty decent and the "toddler tapas" is a great finger food option for small kids who are picky as you can choose what to add to their meal).
Very reasonably priced - olde kids just over £3.00 for 2 hours, younger siblings get entry at a discounted price (I think it's around £2) and babes in arms are free. Good place to meet up with other local parents while the kids play together. If you have a Spree book, they usually have 2-for-1 entry vouchers with the cheapest entry being free.
It's upstairs, so if you have a buggy, you'll have to negotiate that and it makes it impossible for wheelchair access, but that's the only problem. There's a little bit of room at the top of the stairs where you can leave your folded buggy. You turn in your shoes at the counter when you sign in and you can leave your jackets there too if you like - it's all put into numbered cubby holes till you leave.
They do kids' parties which are great for younger children and very reasonably priced. Parties involve play time in the centre, then food and games in the "party room" and a visit from KC Kangaroo himself.
KC Kangaroos is right on a bus route so getting there from the city centre is very easy (#11 and #12 bus go right past it - currently £2 from city centre to there).