why not just save activity info in localstorage?

It's a decent course and I appreciate the effort. I'd rather have given my consent to being put on a public leaderboard though.

Looks awesome, but you might want to say this explicitly on the landing page.

I also came here to the comments to ask why I would want to hand over account information on an unrelated service.

I did not follow the Meteor course, but my impression was it was trying to get my email address to sell me something later on

Perhaps a short sentence in Gray near "Next Lesson" telling you will never sell emails (or similar) would help