How to make real-time shadows like in Dungeon Hunter 4 on mobile platforms?

I found that Dungeon Hunter 4 has very high quality real-time shadows for all characters in scene, and even self shadowing could be found on the avatar if you zoom the camera in. The shadows in Dungeon Hunter 4 are very clear and high performance.
Does anyone know what technique and optimization trick do they use to implement this?

Looks like regular depth map shadows to me, but fairly high res or possibly just extra filtering in the Shadow map shader.