If you want to create your own cool games, you have to face a few choices and you might need to put in a lot of work if you are okay with that so let me tell you that first before you continue.
First you have to decide what kind of game initially should your game be. One of the possible choices are:
and many more.
These are just typical for beginners except strategy that is a personal preference of mine but might be a bit more difficult to start with. I would recommend escape flash games for starters since those are the easiest ones to make, followed by arcade that are also reliably easy to make.
Secondly you need to decide whatever your game will be a desktop version, what kind of graphics do you want, do you want to make your own 3D game and things like that.
I would recommend you to go with flash games since they will be easiest to make and then starting off to desktop version and more complicated games if you are really into those.
As for me I actually like playing flash games since they are quick and fun, but yes if I want to dedicate myself to some serious playing I would go with a desktop version.
Then again if you are just beginning I would highly advise you to start with something easy.
Later on you can get more experience and knowledge so you can move on to things and in the mean time you will also have your flash game working.
Next if you would like to make flash games, you should know how to code in flash. In order to do this you need to learn about Flash and ActionScript, which is much easier than learning how to code c or c ++ for example and learning opengl or directx, but of course if you do learn them too then you would become a pro.
OK so from here I would recommend you to just pick up a book (or find one online) and start learning about Flash and ActionScript. Some tutorials are pretty nice, however most that I have checked do not cover enough so that you are able to put your individual input into practice, but they are mostly teaching you how to create one genre of the games which might not be good for you if you want to actually make the game on your own.
Also you might not want to read in details in the later chapters of the book since if you are a gamer and not that much into coding, chances are that you might get bored … to get the solutions for the problems that you need online, there are many solutions out there once you start understanding the basics.
Well, I hope that I have been helpful to you guys and hope to see lots of your own great games soon.