Create a high-definition, detailed full-body concept art of a fuchsia-skinned, long, limb-mutated nightmare skeleton character, inspired by Phyllis Bone and the movie Alita. The character stands still in a dark, eerie forest with UFO aliens visible in the background, reminiscent of a Blu-ray image. The atmosphere should be foreboding, with detailed shadows and a sense of tension. The style should be similar to concept art, with a smooth and detailed render suitable for Unreal Engine 5.