Thanks for playing! The shield, portal, powercore, and enemy models are by @drxrobo on Twitter. Met him through a mutual friend.
The rest of the art assets are from an asset pack I got a little while back.
The shield is animated procedurally. I'm just rotating the shield face by my desired speed, then rotating the smaller gears by the speed x gear ratio. Surprisingly simple to do and the result looks and works better than expected!