With Scratch we can create video games online, from its web platform, and publish them on the same web. I could download its source code and use it, as many others already did (see Scratch modifications). Unfortunately, we need programming knowledge to use it. Actually, Scratch is mainly for teaching kids to code.
I also found editors like Construct 2, GameSalad Creator and many others (just type on Google: create a video game without programming). With those editors we can create video games without coding. Unfortunately they are neither open source nor web platform. They need to be installed on Windows or Mac.