I don't know the number, but the puzzle after "Watch the Gap" (two buttons, laser grid, malfunctioning dispenser) the level begins with two buttons and a hole on the upper left. Problem: It's not clearly indicated to the player that the first button is connected to the door up top. Took me a good 30 minutes (and help from a friend who had pretty much been following me, though making better time) before I noticed it. Add some blue dots up the wall, I was under the impression that the button didn't do anything but combine with the other button to open the door directly in front. So I tried to vertical fling jump up to the hole, only to find nothing to portal at. Another level...mmm...three buttons in a row, two cubes, and a turret near the door. Made it through without trouble, but lacking the 3rd person perspective of the flash version I ended up with 1 less cube than I started with instead of 1 more, because I didn't know when to pick a cube back up (or what leaving it on the button DID). Had to backtrack and collect them. Minor annoyance. Level 39 lacks the ledge on the "left" that the Flash version had, making it extremely difficult to reach the turret and the two cubes. I kept making it up and then walking off the edge as I was reoriented to vertical (had to walk backwards based on my infinite loop setup and when reorientation took place that put me down facing the turret and I'd walk backwards off the edge). Level 40 needs help. While I admire the creativity in making a 3D version of that map I got lost easily and couldn't figure out how to proceed (without watching a walkthrough of the flash version). More glass? End boss was difficult only because I didn't realize what action I was doing (or not doing) to hurt it. Ended up running around trying to stay alive a lot before I connected the dots. By that point it only had one hit left to go. Actual exit afterwards needs more indication that it's there. Yeah, I know, it's the only actual exit but I spent 5 minutes trying to find another way to go because I didn't hear/see it open. Beyond that, great job.