When you submit to that page it goes into a queue for our team to review. At the moment we haven’t had a chance to review it as frequently, but please do submit if you would like it to be considered when we do review.
At this time, it’s possible lesser known tools may not be included them as the location where these tools appear is limited in space. In the future we may change how we process these tools when we update how the UI there.
In the meantime, creators can still use tags on their project pages to identify what tool they are using without the need for any special approval.
Thanks
Edit: I’ve gone ahead and added Orx for you, looks like an interesting engine.