2 1/2 of the makers of the L4D(2) mod Dead Before Dawn went solo and created THE CORE.
8/10 -
I enjoyed the gameplay. The first chamber was really tricky to figure out and that level of difficulty didn't drop. The mod adds another layer of confusion atop of what was already there with portal. I would've liked to see more gravity-defying rooms like in the floor of the first chamber - they are mind bending.
Overall: 8/10. It's pretty well polished and is a good challenge to those who think with portals.