Creature, a 2D animation system from Kestrel Moon Studios, just added real-time morph target support for game engines such as Unreal Engine and Unity.
Real-time Morph Targets allow you to create a set of morph pose animations that can be smoothly blended and targeted in real-time while running in Game Engines. You author the morph poses in Creature and export them out to have the functionality run live in the desired Game Engine. This allows for some very compelling/sophisticated animation effects to be achieved in real-time, including the ability to have 2D characters that exhibit pseudo 3D Head Turning effects towards a target direction/location.
You can learn a great deal more about real time morphing in their documentation available here. Or by watching this video: