You can play Anchorhead using https://github.com/erkyrath/lectrote/releases/tag/lectrote-1.4.6
Simply download and install Lectrote. Than (on mac) install the macOS Version of Anchorhead and copy /Applications/Anchorhead.app/Contents/Resources/app/anchorhead to e. g. your Desktop. Now you can start Lectrote and open Anchorhead.glorb from this folder. Will work the same way on other platforms. I think the itch.io Anchorhead game is simpy a reskinned version of Lectrote. Have fun!