If you want to launch this app at pressing the hardware camera button, you might have to disable the built in Camera app in Settings -> Apps -> Camera -> Disable.
Contains no ads or unnecessary permissions. It is fully opensource, provides customizable colors.
This app is just one piece of a bigger series of apps. You can find the rest of them at simplemobiletools.com
Allow customizing the app launcher icon color
Split settings into subsections
Couple smaller bugfixes and stability improvements
Simple Mobile Tools