2 hours ago, Finalspace said:

Well, you push the "Follow" button above the thread you can choose from a set of subscription options...

That's true, though it implies I know the thread exist in the first place! If you now where to create a challenge in the new section, how would I know?! Maybe I would find out a month later  

My idea is to subscribe to the whole sections, so every new challenge is notified.

Or maybe it could be achieved with the current tools, just by keeping a locked thread where only sections mod can write, everyone subscribes to that one thread and every new post in there is to alert everyone of a new challenge

Ah, never realized that, apologies!

Forum is at https://www.gamedev.net/forums/forum/81-gamedev-challenges/. We'll need to coordinate with Moderators for sticky management, but we'll get it going and figure it out.