[SP] Gather
Well, this wasn't as bad as I initially thought it was going to be after thinking you were going to make me practice my bunny-hopping for the first cube. Thankfully you have more propriety than that. But making glass that lasers can't pass through seems borderline. This was a fun map to play; as always the design work, to my untrained eye, seems impeccable. I like it less than some of your other maps only because maps where the hardest thing to figure out and accomplish is to get the cube aren't really puzzles (at least, in the traditional sense of the term). But I would highly recommend this map.
Also, the goo issue occurs in the exit room as well.
Evil as always! I had to close the game down for fear of throwing my laptop at the wall....
Solved 
If my solution is correct, last move was really evil.
Is X fizzler disabler only for challange version? I didn't use it at all, but I have an idea how to use it, to take funnel to the final room.
Design was simply stunning. Puzzle was really good too, especially part with
Thank you so much for this brainteaser, looking forward for more
@rogerL Thanks dude! I only did that little glassbox under the X catcher to prevent some unintended solutions that grayarea found. If it's not transparent you can barely see the catcher... Have you tried to finish the more challenging version?
@Jacu Thanks, I'm happy you like it. Looking forward to see you first map. I'm sure you have something evil in mind 
Btw you should try to finish the challenge version ( X fizzler is only for challenge version yes!) and I think none has found the Easter Egg yet
Yeah, I could tell why you did it, but it's just a bit of an anomaly when you use the same texture under the fizzlers in the first room and the laser passes through it there.
Also, two very minor things I noticed: one, a floor button is labeled with a moon, but what it activates (and deactivates) is not labeled, and, two, conversely, the lightbridge is labeled with a square, but the button that activates it is not. Since their respective associations are pretty obvious, it doesn't really matter.
As for the challenge course and easter egg, I have a savepoint just before pushing the button and I will go back and try it once I've recovered from the normal course. 
Yeah, I could tell why you did it, but it's just a bit of an anomaly when you use the same texture under the fizzlers in the first room and the laser passes through it there.
As a map maker, I've run into this problem a few times. Often it's crucial to maintain visibility, but you don't want a laser to pass through. It's a shame that there aren't more types of glass and there's no variable opacity control (that I know of). I've tried to use a darker glass texture for laser-opaque surfaces but it's never obvious until the player experiments with it.
Definitely a tough one! Had to burn quite a few brain cells to get through! Good map Mark 
Very clever, I'm afraid to start the challenge version. The only thing I wasn't too fond of was the cube button trick in the beginning, which I discovered not through logic, but by angrily spamming the button
And I want that damn companion cube....
90 minutes in and I got one cube......
Don't feel bad, that's my status, too.
I still haven't had time to finish it intended way but I think I'm pretty close. Also I found an unintended solution and told marKui about it but I decided to put the pic here also if any of you are interested.
Unintended solution:
My maps: Bits , Color Me Rainbow and Spank Me Skyward