It's a fun project. It uses some of the complex UI design, like the custom painter. Custom painter is mainly for the top AppBar. The title uses 'gloriaHallelujah' text style available in the google fonts package. The zombie animation is made using the rive web app, & controlled by the rive flutter package.
Note: I thought - "Instead of a simple counter app, the @FlutterDev team can provide a simple game like this."