Brain Battle was introduced in Destroy All Humans! 2. Instead of just disguising himself as a human, Crypto went up to a human and commenced Brain Battle in order to Body Snatch. There was a beam of red or blue light: blue was Crypto's and the red was the human's. If blue won, the Brain Battle was complete and Crypto Body Snatched them. If red won, then Crypto had to start the Brain Battle over again. Inside the human, Crypto had a limited time to be inside of them until their health depleted and their body died, but Crypto came out good as new. Plus, you could Sprint while in a body.