First two were much easier for me, mostly because I was using its solution in the first map (as if there were not portalable surfaces outside the room). Three and four were quite difficult, but unfortunately, not a least bit satisfying (these two terms are not synonymous FYI). The laser puzzles are inherently prone to small mistakes, and constant fiddling with the cubes removes all the fun you could have given to your puzzle, hence my negative opinion. I wouldn't call the last one to be "master" difficulty, since the idea to get the cube out of the room is implanted already in out brains (and I've been solving the rooms with one cube from the very start). It's the idea to a) put the other sube at precisely the right angle, and b) drop the cube and use the next one to fall into the silly lock outside that might have confused some people. So, yeah, an hour and a half wasted on these two puzzles, and gained nothing but frustration. But hey, I solved them.

I wonder if I wouldn't like X-River more as a 8-chamber series (or at least 5 chamber series, 1-4 + 5 + 6 + 7 + 8 - or any other combination with 6,7,8 as standalones - to let the harder parts be on their own). It takes long enough to solve them (well, at least part 6 for me) and the player can get bored solving it as so long at once. Which makes them never get to the final puzzle.

I managed to get killed once by a laser :) I forgot it is even possible...

Very smart, geommetrical puzzles.

7 was the moment I decided to give up (or rather I was too lazy to make 6 again after my computer resterted suddenly while I found the basic idea for solving 7). It's cleverly designed but I wish there was more than one autosave possible... Too much geommetry for me. Once I figured how to do part 6, it took me long time to adjust the cubes, especially as due to laser beam it was better to adjust it without final portal to not get dumped by laser.
Watched the solution, 8 is indeed tricky. It would take a bit to figure it.

excellent puzzle!

Puzzles are very good. I hated the claustrophobic laser rooms. Nearly impossible not to get touched by a laser. Saveing progress in this puzzle is needed unless you want to start all over. There appears to be a player trap on the last puzzle. No way to get out from the tractor button area if players visit there...

Good work again, I had to see nr7 (taking to long); in the last (not the most difficult) I forgot some moves of the initial rooms; there is a couple of ways to solve the same room as long as we have the right white surfaces available. nice set of puzzles.

DISCLAIMER:
Read my profile before reading the rest of my comment!

They are challenging, but this is why I don't like and prefer other puzzles, like the one that I said was my favorite of yours.

Try my SP map?
http://www.steamcommunity.com/sharedfiles/filedetails?id=192976369
Try my COOP map?
http://www.steamcommunity.com/sharedfiles/filedetails?id=181160432

@ DeathWish808. I saw your video. This is the first time I see someone solve my map in blind Run, if you liked to play, well I loved watching you, and makes me really happy. You very well understand how X-River works, resolve in just 18 minutes is very impressive ! Well done ! Thank you very much for your video :-)
(My best map that is -The Cage- ! If you want to try http://steamcommunity.com/sharedfiles/filedetails/?id=133228133)

Excuse my English but I am French and I use a translator ! ^ _ ^ '

OK, finished this one and am sad to say that... YOU HAVEN'T MADE A PART 3! LOL.

Wow! I really wasn't sure how you were going to elevate the difficulty without major changes, but you did a fantastic job. Another big thumbs up from me!

Super clever on all of them especially the last one. Definitely had me thinking the whole map through. I have a headache now thanks to you. haha.

@p0rtalmaster - I did see a way or 2 where you could "trap" yourself with the only way out is killing yourself. That said, it's a non-issue for me because you'd have to thoughtlessly put both portals on the exit side (#8) and to fix it would mess things up. (If in doubt, F6)

Well done!

Blind run: http://youtu.be/V7rdwlLzug0

...and possibly part 8 as well. Are any slick tricks needed for parts 6-8 (I'm not talking about speedrunning here)?

I managed to get trapped at part 6....

Very nice and VERY hard :) I would have to say though that 6 was the hardest. All the same, all the rest were also very challenging in their own right. Nice job!
My Workshop

Good game Diego :-)
--> Official Solution to X-River (PART 2/2) : http://youtu.be/OMbv1RexQZQ
Thank you for playing !

lvl 6... you might to be kidding me

Almost 2 hours to do Parts 1 and 2 all 8 X-Rivers, Nice job dude!

YEAH! Last chamber is tricky i didnt know witch cube do first! But i took the more time to do the 6th. Destroi the cube and let the new one drop on the portal was nice, them open a portal to the laser http://i.imgur.com/Ddufg.jpg

Got sutck in 6 on the other side of the river without a box and no way back

Love it.

Jep, Part 2 6-8 made my brain smokin ^^

Part 2 is a bit hard, but ill beat it. :)