As i've told before, i was messing around with UDP code stuff. Never programmed in Python before, but after some research, i could adapt MasterMind UDP library (that's on Pygame site) to work with Construct.
So, It's a simple program, where server will move the red player, and client will move de blue one. Connection is done via UDP as said, but there is no optimization or prediction or etc here, just studying socket stuff. It's rough, but works. You can connect to external ip, if port is properly forwarded.
I will try to advance on my experimentations and refine this thing a bit more. At the end of post, the source code for Construct is attached. And below, some links about UDP in Python and in general gaming:
http://www.pygame.org/project-Mastermind+Networking+Lib-859-.html - Mastermind Networking Lib on pygame.org, from wich my code is based uppon.
http://gafferongames.com/networking-for-game-programmers/ - To me, this one is a must-read article series. It covers the basics about game networking. take a look!
http://gafferongames.com/game-physics/networked-physics/ - From the same guy, it covers aspects like client prediction, and i think it's focused on a FPS approach
Cap file attached. Used Constructed 0.99.84.