Gamedev here and one thing I've noticed amongst peers is an emphasis on good practice over algo knowledge. Mastery of debugging for example is something to look for.
Now when I find a a candidate, usually via Github or their dev diary, I can usually tell from the work itself that they have the talent and skill.
But I can also employ a very simple screen: implement a basic image processing op using the Pixel Manipulation API on an HTML5 Canvas2d. Say Gaussian blur of an input bitmap. Not uncommon to get a "Javascript Expert" who can't even render a bitmap to a canvas. But a solid prospect with good engineering instincts will be able to wax poetic about low and high frequency noise in the image, convolution kernels versus Fourier analysis, and perhaps whether WebGL might not be more performant ;)