If Doom and SA1 made sweet, passionate love to each other, this would be the result. The controls certainly take some getting used to so the first playthrough can be a bit frustrating. But eventually, they will start to click and once they do you'll discover an incredibly speedy 3D platformer with gallons of love and care seeping out at every seam.
When it's actually finished (please don't be a silk song situation) this will be on par with Mania. And the best part: IT'S FREE!