Flying Eagle Challenge is an action game developed for Mac users to play while they're on a break from work. The app doesn't provide you with levels; instead, it offers you a single challenge where your objective is to avoid as many trees as you can.
When you launch this game on your Mac, a window appears on your desktop where you can configure display and control settings (this window is accessible only at app restart). Afterwards, you can click the Play! button and try to obtain the highest score possible.
The app keeps track of your highest score, allows you to change the control options if necessary, and play the game in fullscreen or windowed mode.
Nonetheless, I found this game to be pretty challenging and annoying. With a simple click I could easily hit the trees and my maximum score was 5 (managed to avoid 5 trees). As you will probably notice if you install it on your Mac, this game is similar to Flappy Bird, a popular app that annoyed many smartphone users.
With that being said, I'd say it's not worth installing Flying Eagle Challenge if you care about your state of mind. This app was designed for users with a lot of patience.