Do It Your Bloody Self: DarkBASIC For $0
Ah, DarkBASIC takes me back. Its various iterations made regular and hard-fought-for appearances on the coverdisc of the magazine I used to work for, and at the time were one of very few ways for amateur types to make a standalone videogame of their own, without having to learn coding or resort to modding. Never got around to trying it myself, but I got the impression it was pretty decent. Take a look at (and play) the kind of stuff that's been made with it here and here. And now it's free - ad-supported, but it's the full Professional edition, entirely bereft of its former $70 pricetag. Presumably it's a response to the likes of Unity and the Unreal 3 SDK going similarly free - this is one case where a crowded marketplace is only good news. Dance! Dance with joy! Or we'll kill you!
Oh, and DarkBASIC creators the Gamer, er, Creators have another freebie...
It's the FPS Creator, "which enables the creation of rich, engaging 3D First Person Shooter games by people with no previous programming or 3D modelling experience", it says here. It's not a massively advanced engine - understandable, given it needs to be accessible - but it can create stuff that's visually on a par with the original Half-Life, or thereabouts. Creatively on a par? Well, that's up to you. It is free, but carries a few more restrictions than DB - notably, no multiplayer creation options, and you can't make your game standalone. Unless you pay to upgrade, anyway. Not a bad deal, though: if you do create something you're proud of, there's no licensing or restrictions on publishing it. Go to it. Make wonderful, twisted, free things.