Seeing as Flash is going to be discontinued, for many people the Flash platform is no longer a viable platform for web games. Making HTML5 games sucks, but fortunately - there's an alternative.
Haxe is a platform-agnostic open-source programming language and compiler, originally inspired by Actionscript 3. In other words, its a language that's similar to AS3, but lets you deploy your games to many different platforms, including the web, native Windows, Mac, Linux, iOS, Android, etc... And because the compiler exports native binaries, the performance on those platforms is very good.
A few years ago I've started a blog where I published tutorials about Haxe and its libraries, including the popular OpenFL framework. You can find the introductory article here:
Haxe has already been in use for years for many commercial games, including popular indie titles like Papers Please and Defender's Quest. I have also used it for my game Hypnorain (available on Steam), and am currently working on a 3D game called Speebot.
Developers that are familiar with AS3 will feel at home coding in Haxe, so give it a try.
Here's a screenshot for my game Speebot (powered by my game engine YUME), which I'm currently working on.