Reaktion : An audio reactive animation toolkit for Unity.InAudio 2 : Add great audio to your game in seconds with the new layered music player with crossfading and gap-less transitions.Audacity : Multi track recording and editing software.TakeDown Animations : 12 takedowns animations package.Mixamo : If you have an account then these are all free!.Melee Axe Pack : 55 mixamo animations for axe-wielding, skull bashing, dragon slaying barbaric types.Magic Pack : 55 awesome magic animation from mixamo.Huge FBX Mocap Library part 3 : Conversion of the Carnegie-Mellon mocap library with 2,534 mocap animations.Huge FBX Mocap Library part 2 : Conversion of the Carnegie-Mellon mocap library with 2,534 mocap animations.Huge FBX Mocap Library part 1 : Conversion of the Carnegie-Mellon mocap library with 2,534 mocap animations.Animation Baker : Converts Mecanim animations back to legacy animations.Animancer Lite : A code-driven replacement for Unity’s Mecanim AnimatorControllers based around the concept of Dependency Injection: instead of using names or hash codes to identify predefined states and parameters, you simply pass the desired AnimationClip directly into the Play or CrossFade methods.

Google Analytics Plugin : Allows game developers to easily implement Google Analytics in their Unity games on all platforms.

Unity Movement AI : A library of steering behaviors to help your NPCs move around your game.

TopDown AI : This is an example of Top Down Shooter AI.

Panda BT Free : Panda BT is a script-based Behaviour Tree engine which allows the authoring of complex, scaleable and reusable logic for your game.

Goap : Goal oriented action planning AI in Unity.

Crystal AI : A Utility based AI for C# and Unity (can only use free version in free games).

Behavior Bricks : Behavior Bricks is a state-of-the-art engine for Behavior Trees (BTs) along with an intuitive visual editor.

You may also be interested in taking a look at the quality assets that I use regularly to create my scenes – best of the best environmental unity assets.

Free character unity