Create a detailed pixel art illustration of an anthropomorphic bear. chibi, piercing, and a grim expression. Its fur is marked with intricate tribal tattoos. Set the scene in a dark, atmospheric environment with a large, ominous sun or moon in the background, and swirling clouds. The color palette should consist of dark earth tones with accents of gray and white, capturing a moody and mysterious vibe. hd quality --ar 2:3 --v 6.0 niji