Keep in mind that these apps have not even made it to the beta phase of development yet. They may be unstable. 

By using these apps and providing the developers feedback, you are in turn helping with the development of the app. Take an early peek at these early access and unreleased apps and games.

This app shows the change logs for all the apps that you have installed. Handy if you like to know what has changed in your apps.
A new app of it’s time. Create your own Substratum themes.
Island allows you to run multiple instances of your apps. Kind of like adding another user to your device, but without actually adding the user.
An interesting icon pack that includes widgets. Sort of has a hand-drawn feel to it.
A fun multiplayer racing game. It has a blocky-3D feel and an interesting overhead camera view.