Alright, so I finally got the opportunity to test the game. Disclaimer: I have never played Disillusion before. I played it for around 30 minutes.
The download
The hardest part was actually downloading the game. For some unholy reason, MEGA does its decrypting client-side it appears. As a result this makes Firefox uses 2 GB of RAM which in turn freeze explorer.exe (Windows' interface) completely until the browser crashes. I bypassed this problem using the MEGA app (which I already had installed). I know you obviously have no control of this, but I just wanted to point out this was a thing.
The Extraction
For some reason, that zip file cannot be extracted using 7zip. It returns a "unknown interface" error. I bypassed this by using Winrar which did not have any problem.
The game
The first thing that I noticed is how the game window had a vertical and horizontal scroll bar. If my memory serve correctly, RPG Maker MV had this cursed thing were the game is rendered inside a Internet Explorer/Edge frame. I guess a similar thing is happening here. Quite sad as it completely shatter the immersion. Furthermore, the game lacks a true screen mode. I know that RPG Maker VX Ace had one by default, so I assume this is a feature that got nuked by Enterbrain or something. Much like the scroll bars, this too break the immersion. There may be a way to fix this with third-party script/plugins
Past the title screen and the intro, the first thing I noticed is that the game run on 10 fps (probably caused by my pc configuration and RPG Maker being RPG Maker). Now, the game is still playable and it arguably fit with the aesthetic of the game.
While navigating the first room, I was not a huge fan of how you move in the world. That being said, my interest in the game suddently peaked by the first scene Mel is in. I immidiately wanted to know more about this strange waifu. The concept of exploring people memory seemed intriguing.
To my disapointement, the entire game seem to made of labyrinths. There is empty halls everywhere which IMO just seems like needless padding. The game implies that the goal is to locate "point n click scene triggers" (which I assume are the memories Mel was talking about) yet I have only found one (the church scene). Mel seem to also completely dissapear as she was not present in any interaction I did. I also notice that when you talk to NPCs, they dissapear. Knowing RPG Maker, this means that you probably used switches. This imply that this has some function, but I don't know what effect this has in-game.
It is also became obvious that some maps are literally just a tileset switchs. Many NPCs are also resused (such as the reference to a certain website).
On a positive note, this is probably the best game that use of those cursed 3D RPG Maker scripts that I have ever seen. The atmosphere really give a strange and alien vibe. This game feel like a horror game you would see featured on Youtube channel such as Nexpo. It sure gives heavy Worlds.com vibes.
Reccomendations
Now, as previously stated I have not played the original Disillusion. All I know is that it shares a similar art-style. What I am about to suggest may go against the "soul of Disillusion" or something. Keep in mind I don't have the full picture of what this game is trying to do.
If I were the architect of this beautiful alien nightmare, I would do the following. Instead of crawling through a tower of labyrinth, you would explore some kind of vast castle or domains - basically smalled maps organized in a less randomly manner. The player would be able to go everywhere after a brief intro/tutorial Kinda like a very strange version of Peach Castle from Super Mario 64 (btw, this game reminds me of the Build 3313 ROM hack in some ways). The goal would be to locate "memory spots" that trigger the point n' click sequences. Each sequence would have a mendated Mel interaction. Once all memories gathered, the player would need to go to a designated spot to trigger the conclusion of the story.
I would also focus my attention on making every area as unique as possible. I would try to avoid repeated NPCs and scenery.
Hope this helps.