With Construct 2, it's possible to put together a very basic "Flappy Birds" game in around 10 minutes!
You can download all the images and the Construct 2 Capx on the left and you can play the completed game here.
If you get stuck at any point, open the attached CapX file and take a look at it to see what's different!
Create a new project and add two layers "Start" and "Game". Set both these layers to have a "Layout Size" of "400x500".
In the "Properties" window on the left, click "View" for "Project Properties". Set the "Window Size" to "400x500" and under "Configuration Settings" set "Fullscreen in Browser" to "Off".
Your project should now look similar to this: