I'm making a game on iOS, and I'd like to know if it's possible to make a "pre-order" on my app.
Example : I want to release my game on May. Is it possible to publish it on March but just for "pre-order" ?
It's a good way to see if the app is appealing or not.
Apple inc. has strict guidelines for App submission and it review. You can have a look at this.
You requirement for pre-order app submission violates oint 2.9: Apps that are "beta", "demo", "trial", or "test" versions will be rejected.
This link will give you more insight on the process.
So you have to either cut-short the game of yours and submit it as full-functional app. Apple doesn't care how much level your game has. And in later on-releases you can add the levels and updates. But make sure you adhere with the guidelines and do not display the "demo/trial/etc".