I was wondering if someone knew of good 2d AI libraries? The game I am trying to create is top-down view with C++ on directX. I need NPCs to be able to flee, avoid projectiles and/or obstacles, find paths(avoiding obstacles, perhaps even moving obstacles?), some crowd management would be good too. I was thinking about using OpenSteer but I am not sure if it works with 2D. Thanks.

check Chapter 3 of the book "programming Game AI by Example" the topic "Steering Behaviour" it contains all the algorithms u mentioned.

also there is source code for this book on the internet written in C++,
u can get it, embed it in your engine.

Thanks! I'll check it out.