I want to do a Project on my own personal property. I only want people I invite to be able to see the project. Is that possible?
Yes. Make it a “traditional” project. If you read about the different kinds of project, you’ll eventually find mention of this, although it’s not one of the main kinds they push. I used an invitation-only project like this for my botany class last spring.
If you really mean that no one else would be able to know that the project exists, then no, that can’t be done. All projects and the observations they contain are visible to everyone.
If you’re looking for a collection-styoe project, you can probably just build a URL which will filter by your desired parameters. Then you can send the URL to people with whom you want to share the ‘project’
Another potential tool is to set the observations’ location privacy to Obscured. When the location is Obscured, only those users you designated as trusted can see the actual location.