Okay. While I have helped given feedback on earlier builds I can see that you have changed the game a bit, and added new mechanics since I last played. So, let me give a new analysis from my perspective of playing. If anyone reads this who hasn't played yet, please be forewarned that there are some puzzles which can be spoiled by reading this. So Spoiler Warning
1) Translations - I feel like you guys did a good job on this one. Earlier one of my problems testing was the inability to tell what I could and could not do because I had to learn keys by error. The fact that your english translation gets the job done and is written in a clear concise way to help new people is good.
2) The Difficulty - I feel like your first 8 or so levels are very well designed. They show clear cut answers, give you the tools needed to pass them, and outside of some minor timing are pretty solid. However, if I had to describe the difficulty of the puzzles in your game, it is very much like Kid Icarus for the NES. There is a very sudden wall of difficulty that appears out of no where. The game becomes very heavily about perfect throwing and perfect timing with only one clear cut way to get past any puzzle. The fact there is only way through most puzzles after the starting area is fine, but the fact that these puzzles also require extremely high amounts of timing, positioning, and trial and error makes them far more tedious than originally thought. I believe when the game is longer and you have more puzzles to fill the distance, then these spikes of difficulty will ease up. That said, I want to point out right now something that you did exceptionally well with, and that was solution foreshadowing.
One of the puzzles which left me the most frustrated was the two sentries in the hallway. In an earlier rendering of the pre-demo builds that I had been trying, you had a bad problem with the solution not matching logic given to you by previous puzzles. However this time around the solution was brilliantly set up and I have to applaud it. In the previous puzzle you showed us that the destruction of a Logic Cube will create a lot of noise, enough to get the sentry's attention from VERY far away. You showed this in literally the puzzle before this. You allowed the mechanic of cubes destruction = LOTS OF NOISE to be revealed to us as a penalty to avoid in the puzzle before it, so that we hopefully see and use it in the next puzzle which is the only actual solution to the puzzle. This is Good Game Design here.
That said, I feel like as a person who enjoys puzzle games, the spikes when they occured were very sudden. All in all, aside from the twin sentries which is in my opinion the only puzzle which requires you to use the concept installed by the previous puzzle to pass through it. Some puzzles require you to use a ledge to hide which I feel should be explored in before the jumping maze puzzle. All in all, I just feel like when you can expand the game to have more puzzles, the difficulty wall most of us end up feeling won't happen as harshly and will be much better. I suggest actually throwing in a couple puzzles from the earlier pre-demo builds. In particular I suggest the one where you had to walk on a ledge to cross silently. ((The last puzzle of the first pre-alpha build.))
There is one puzzle which I feel like you could improve on in this demo and that was the very final puzzle with the two teleporters. Having some kind of colored line linking each of the two teleporters together would help avoid confusion on which teleporter does what, especially if you have puzzles later with numerous teleporters.
3) Environment - You guys took one of my suggestions from the pre-demo and made the game feel SO much bigger and it shows. I really like how much more polished the game looks. While you do mix the different colors, the portal like ambience no longer feels like a copy cat or a clone. You added in many details that truly makes the game feel unique. Walking through a glass hallway and see the large empty space was incredible and to have it foreshadow the fact that the upcoming puzzles were a large open space was truly a wonderful feeling! That large area and seeing all the puzzles that awaited me at once was incredible. I'm left with a very solid and good looking ambiance. From the earliest builds, you've taken what looked like a portal clone, and made it appear truly unique as its own standalone sci-fi puzzle.
4) Puzzle Mechanics - Having played earlier pre-demo ((Pre-alpha?.)) builds I do have a bit of an unfair advantage to review and judge this. However, allow me to give my personal opinion on each mechanic itself.
4a) Sentries - I notice that a common thing that people ask about is to show the limit of the sentries vision. I am torn on this. I found in a couple puzzles, I wasn't sure what their vision limit was which caused me a lot of stress and concern. Part of a puzzle game is to show clearly what the rules of the game is. What we do with these rules is how we solve the puzzles. The problem with the sentries is that their rules are... blurry. While we can see the edge of their vision on the sides, not knowing their distance limit is uneasy. Not knowing how close we can get without crouching, how far their attention is garnered is very questionable. However, when it comes to sound, I believe they are fine as they are. I personally don't know if having their sight limit being so unknown is a good thing or a bad thing.
4b) Throwing - I think this is well executed now. From the earlier Pre-demo's its been improved a lot especially by showing where it will land.
4c) Teleportation Units - OMG THESE ARE SO FUN EVEN WITHOUT A PUZZLE! Okay, all puzzle hype aside, I feel like there is one problem with them. When there are multiple teleportation units there is no way to tell which teleportation unit connects to which one. Having some kind of cosmetic line to show these links would be nice.
4d) Movement - Your ability to move, crouch, climb, and such have been improved a lot since earlier pre-demo builds. Honestly, the ability to finally climb up a ledge with a cube is such a welcome relief. I hated when you had to throw them up the ledge. All in all, I think this is plenty fine.
4e) Triggers - The triggers to open doors and activate and deactivate different things in this game have always been just satisfactory to me before. However, this demo showed you using triggers for more things such as timing puzzles, ledges raising and lowering, and many more effects. Honestly I think this is a good mechanic and its being well used.
Honestly, in my final opinion, this demo shows the amazing promise of this game and its puzzles. I can not wait to see what you guys do with this game. The environment looks spectacular, the character looks good, and the mechanics of the game are well designed. Speaking from a mechanical standpoint, I feel as though this demo shows the mechanics of the game in a very solid and well designed light. I just feel like there is one puzzle which is a massive difficulty wall that everyone talks about because while the solution is foreshadowed, it isn't played upon before it. I look forward to being able to buy a copy of the game myself when its out.