I used the Sketch "Delicious" free UI Kit for a food recipes app. It includes 11 pixel-perfect screens. I just added Proto.io interactions and created a great prototype! This Delicious UI Kit was designed by Robert Anitei Sketch source: https://www.sketchappsources.com/free-source/1765-delicious-ui-kit-sketch-freebie-resource.html

Using variables on a slider to control the Brightness and Hue of a light bulb

Movies & Series App project Design Credits: https://www.sketchappsources.com/free-source/2896-sample-iphone-x-movies-app-sketch-freebie-resource.html

A simple endless runner. You can jump by tapping the screen, hitting the space bar on your keyboard or hitting the up arrow key.

Travel app (Part 1) Work in progress of Travel project Credits: https://www.sketchappsources.com/free-source/2947-travel-app-ui-kit-sketch-freebie-resource.html