There can be a small credit system where you can use those credits to advertise your game. There can be like, a small banner on the far left or right with certain projects that you advertise. I'm not sure how you can get these credits, maybe every day you can get 2, but the more credits you put in, the more it appears! Though maybe this doesn't have to be everywhere you Scratch, it can be in the Scratch news page, you know that one? https://scratch.mit.edu/. This will help tremendously for unpopular but good Scratchers and projects. I hope you take this into consideration! ^^

So, would it redirect to, for example, https://scratch.mit.edu/ads/12345?

That sounds cool, but unless you find a way for the ads to both be moderated in a way that the Scratch Team isn't stressed (meaning they can choose which ads are appropriate for all ages and which ones aren't without being given too much work) and not using up too many resources, then this is rejected by the Scratch Team (or in this case, a former Scratch Team member):

Za-Chary's Official List of Rejected Suggestions (Current/Ver. 5) wrote:

7.8 Project advertisements on the Scratch website
Some users are interested in having advertisements around the website which advertise Scratch projects or studios, even if they are not paid for these advertisements. However, it is unclear how projects would be chosen to be advertised. Also, this would require a Scratch Team member to ensure that inappropriate projects are not chosen to be advertised, and the Scratch Team does not currently have the resources to do this.

You can find the official list of rejected suggestions here: https://scratch.mit.edu/discuss/topic/343602/

Oh okay. I mean it could abeen cool! I am making a Warrior cat game currently, and I wished it could be advertised more.

-flowerx wrote:

Oh okay. I mean it could abeen cool! I am making a Warrior cat game currently, and I wished it could be advertised more.

You could advertise it in the Show and Tell forum. I hope this helps.