Maybe I'm blind, but I don't see an option to follow a game. Is it supposed to be in the left menu?

Yes, it's supposed to be under the game cover image and info, and above the left menu options. The button won't show if you are not logged in by the way.

Well I am logged in but it's not there for me. I'm using Chrome on MacOS.

Disable your ad blocker (or better yet all extensions you may have installed) and see if it reappears. This is a known bug that happens with some ad blockers or other browser extensions.

Thank you Timmiluvs, disabling my ad blocker helps!