Shabadage over on the forums has uploaded some cool, free open-source stuff to get you going in the world of Clickteam Fusion 2.5. These examples are pretty cool and demonstrate how simple you can devise a game engine in Fusion 2.5 rather quickly.
Shabadage has managed to comment most of these in the event editor, so they’re quick and easy to download, open up in Clickteam Fusion 2.5 and learn from almost immediately.
Whilst these engines are not all necessarily full game engines, they do provide the foundations for you to learn from and then develop further into your own desktop and mobile games (even console games with the new UWP exporter).
You can check out the forum thread here which contains links to some of his work uploaded to the Clickstore.