Thank you all for your inputs.

In answer to Infinisearch, he has shown interest, in that he got into designing his own levels for some xbox games. Which is why I think developing/building is more his line than programming.

To be plain, it's very hard to buy for him. He really doesn't want much other than an Xbox One (which I can't afford). I see doing this as a relatively inexpensive way to offer him a chance to explore building games, so that if he doesn't follow through I haven't spent a bunch of money

Right now I'm leaning towards getting a good beginners book on Game Maker Studio and downloading the free version for him to try. If he really gets into it, I can move up from there.

On a related note, does anyone know of a way to get a full ISO of the Game Maker Studio free version? In other words, something I can download so my son can load it if he doesn't have access to the internet to load it from there? The download from the GMS site seems to just be a loader program that goes on line to actually get the content.

Thanks again, all.

On a related note, does anyone know of a way to get a full ISO of the Game Maker Studio free version? In other words, something I can download so my son can load it if he doesn't have access to the internet to load it from there? The download from the GMS site seems to just be a loader program that goes online to actually get the content.

I guess, you'll have to setup an internet connection for him, at least temporarily. Since, after the initial installation Game Maker Studio needs to update itself for some reason. I tried to search for a standalone installer but didn't find any. And still, he would even need to register for a Yoyo Games account initially.

So, maybe you could set up Game Maker Studio for him with an internet connection and then remove it later? :(

On this point, I join fleabay idea, if your son have not said himself that he want to make game, it may be a better idea to get him some game with available and easy moddings tools (the good thing is that you have a choice and with a lot a genre, with Doom, Counter Strike, Divinity: Original Sin, Neverwinter Nights, Skyrim, etc...). That will give him a game, and in addition something to play with when he will want to add himself some content in it!

Game Maker like almost everybody suggested is a good idea too, but if you are able (financialy), I suggest you to get one of this games with modding tools included (of the genre he prefere) THEN to include with it Game Maker and the book about it to add some value about the possible creation of a complete game. I have not seen any suggestion about it, but another option if he is into RPG may also be to take a look at the RPG Maker series, they provide some nice tools to start game making too

I have to disagree with several of the comments above, having started myself at about the same age. It's not necessary to dumb things down at age 13, and indeed the "fake" stuff can be discouraging. Let him loose on real tools and see if it sticks or not.

This would be my preferred method, too. Everyone is different, so I don't know how your son will receive this. I prefer to learn things as is, rather than a dumbed-down version that only has very little things to it, only having to unlearn everything I have learned when it comes to the real thing. Although, I wouldn't go with C++ unless that's something your son really wants to do himself. Unity, or any tools that's using C#, should be a good enough entry point.

Install the free version of GameMaker and see what he thinks. Also a few games that have very good mod tools to let him play around with.

Also it may be that he has no interest in programming but just likes designing stuff and modelling stuff.