There are a bunch of places to play pick-up basketball in Chengdu, though foreigners might be limited and nearly all are outdoor:
1. Sichuan University Wangjiang Campus (east, right off of 1st Ring Road) – go to the courts in the middle of campus near the stadium, recently reconstructed, usually packed with people after 4-5 PM, open until 10 PM or so with lighting when it gets dark, free entrance
2. Decathlon (south – next to IKEA) – new courts, haven’t been yet but I hear good things, I think 5-10 RMB entrance fee
3. Sichuan Gymnasium (central) – semi-indoor courts, 10-15 RMB entrance fee, floor is slick and a little worn, they usually have leagues and camps so it can be hit or miss in terms of whether you can play
4. Shen Xian Shu (神仙树 – southwest near Tongzilin） – also have never been, but I’ve heard they’re nice courts and foreigners play there
I would suggest joining the WeChat group “外国 Basketball”. Ton of foreigners in there and they often set up pick-up games.