You can choose what I work on. I have experience on all of the features that you listed. I have implemented FMOD audio in a few games of mine in C++ (one with some 3D audio). I normally have background music on a loop in the game, and some additional sound effects that are triggered by other events. I am very good at all types of animation (bone kinematics, curve path movement, particle systems and effects, camera control, object motion, etc.). I am familiar with animation that is smooth with ease-in and ease-out transitions, and I use Vertlet integration for other effects and object motion. If you need a navigation mesh, I will have to build one from scratch which I have not done before, but I have excellent source code for A* pathfinding. I am pretty handy with UI too. I did a large amount of UI in Unity for the last game that I worked on. I will have to redefine the milestones based on what you will have me work on and what you want out of it, so let me know what you want. I am flexible with your schedule too.