Ubisoft's Splinter Cell 3DS runs on the Unreal game engine.

Splinter Cell 3D producer Fabrice Cuny confirmed that the development team at Ubisoft was able to implement the Unreal Engine on the 3DS. He states that "It is pretty impressive for a handheld machine, and the 3D doesn’t affect the performance (thanks to my amazing programmers). The architecture is different compared to a Wii or some other platforms that we had to work with here at Ubisoft Montreal."

Splinter Cell 3D is a re-imagining of the 2005 title Splinter Cell: Chaos Theory, and will be a 3DS launch title.

UPDATE: The version of the Unreal Engine in use on the 3DS is the older Unreal Engine 2, not the current Unreal Engine 3, an Epic representative has told Destructoid.