FireAlpaca is described as 'The image editor that can be used readily and easily. We made it possible to provide the completely free download, in order for our products to be experienced by more users from all over the world. It vailable for both Mac and Windows users!' and is a popular digital painting tool in the photos & graphics category. There are more than 100 alternatives to FireAlpaca for a variety of platforms, including Windows, Mac, iPad, Web-based and Android apps. The best FireAlpaca alternative is GIMP, which is both free and Open Source. Other great apps like FireAlpaca are Krita, Adobe Photoshop, Paint.NET and Affinity.
Paintbrush has a very simple interface in which you can draw and paint... no layers, but .png files can be saved. Really, it's a much closer alternative to Microsoft Paint, but I can also do a few things that would be tricky in FireAlpaca.