A mobile ad makes you enthusiastic for an upcoming app … but the app isn’t out yet.

That “hurry up and wait” scenario is the target of a new “Reserve App” feature from games network WildTangent, which the company announced this week. It will be available in the fall.

The viewer simply clicks the reserve button in an ad for a mobile app, and this schedules the app to download when it becomes available. The user can receive an alert when the new download arrives via an optional push notification the developer can send.

The reservation has no cost, and for the time being, this is only for free-to-play apps. Besides ads, the reservation link can also be in social media, video, messages, or other apps.

CEO Matt Shea told me the idea came when he and his son were watching a trailer for the upcoming Star War feature movie, out in December. His son became very excited, but now has to wait months.

While it can’t be implemented for feature movies — at least not while their legal opening venue is a movie theater — Shea said the preview-then-wait situation was relevant to promotions for upcoming apps.

He noted that about one in eight users actually completes the usual process for a promoted app — click on the ad, go to the app store, install the app, and open it.

WildTangent said that, as far as it knows, it’s the first to offer “an app reservation service with a single click from within a stay-in experience that will automatically deliver the app or item to the user’s device when available.” It noted that Google Play has a preregister feature, but it involves more steps, doesn’t automatically deliver the app, and is limited to the store.

The Redmond, Washington-based company says this reservation-and-automatic-delivery lets developers see the demand as the launch approaches, so they can rejigger their marketing if needed.

It also acts as a direct call-to-action that shows the effectiveness of certain ads or ad channels, and it can generate valuable feedback through comments that accompany the social sharing of the reservation link.

Most importantly, it makes sure that those most eager for the app get it.