Fallout: New Vegas - Old World Blues
First mentioned by Silentpony
Want to spend some time wandering the wasteland looking for your missing brain? Fallout: New Vegas has you covered with the Old World Blues DLC. After your character was abducted and experimented on by the "Thank Tank," you'll set out to recover your brain from the evil Dr. Mobius. It turns out that things aren't always what they seem, especially when you don't have a brain.