Didn't play the second version but I did play the third. Visuals look great now. All the objects look much much MUCH better, great job.
Level 1
I only played the new first level a few times but what I found was that the button there didn't really look 'pressed' it looked the same, also the portals didn't look turned off. I honestly thought the portal not working was a bug until I accidentally left the cube on the button and it worked. The final, I guess, gravity slide in level one also failed a few times which was kinda annoying and should be looked at soon.
Level 2
The second level should definitely be worked on. I tried to put the cube on the button. This turned on the, as I now know, wire but I thought it was a bridge to walk over it had no collision and now I was kinda confused. I thought to just grab the cube and put it in the hole with the portal below and jumped. This triggered the portal and shot me up. I was also confused there and just tried to move around randomly to see what I could find. After a while I jumped down to the end and was very confused as to why the level finished. I tried again and now found that the wire was actually a wire and triggered the portal which made me smoothly do the rest of the level.
EDIT: After talking with the dev it turns out my 'correct' way was also an oversight
What I suggest
In general I think it is a good idea to show what direction portals change gravity to it makes a bit more sense and could lead to new puzzles. I also suggest a checkpoint. It's frustrating having to redo something over and over while trying to figure out, in my case, the button.
What I suggest to change in level one is a same kind of link from the button to the portal as level 2 has. Also, to change this wire but I'll touch on that later. Also simply fix that last 'gravity slide' it's very inconsistent. Perhaps also change the location where you place the block to enter the first gravity switch, it feels very out of place now and could lead to a new type of button that changes gravity instead of activating a portal.
In level two I highly suggest to change the wire. I think it would be cool to have a line either dark blue (turned off) or neon blue (turned on) and this also for turned on and off portals. Lastly the level felt a little empty, here I suggest it is a little smaller or is filled with an extra puzzle.
Lastly, add more levels to try out new concepts and be creative. Good luck, have fun, don't die xD.