I want to leave my opinion of Sonic Omens as well as some fair criticism, because I thoroughly enjoyed playing this project and I'd like to see it become the best that it can.

The visuals:
Fantastic. The game looks stunning as it is, and runs pretty good too. The only gripe that I have with the graphics, are the god rays/light shafts. Now I love godrays in games, but they seem a little too strong. I believe that it would look better if they were either toned down a little, or if you switched to something more like godrays with volumetric fog. If you don't know what I'm talking about, just google volumetric lighting and you'll see what I mean, NVIDIA offers their own solution, but I know Unreal Engine does as well. Better yet, here's a link to their documentation:
https://docs.unrealengine.com/en-US/BuildingWorlds/FogEffects/VolumetricFog/index.html
The animation work is very well done, and really caught me off guard. Now's a good time to mention that I went into this with absolutely no clue what I was downloading. I didn't even look at any screenshots first. There were a couple scenes I saw that had some awkward animation and clipping, but overall, I believe that you nailed the emotion and the movement of the characters which can be hard to pull off. Now, I've never worked with Infinity Engine before, but I have always hated its overuse of camera shake. Unless it is hard-coded into the engine somehow, it would be nice if there were a toggle, or a intensity slider that we could use. Even on a high refresh rate display, it's a little much for me.
Despite these minor things, I'm actually really impressed at just how polished the overall UI/User Experience is, especially in the menus. Most fan games, especially those made in Unreal Engine, tend to just crank the graphics and forget the settings, I'm glad to see that you did not.

The Audio:
Very good music. Don't really have much to say except I enjoyed it. The music in the Dragoon E-Zero fight gave me DOOM (2016) vibes which I loved. Also, the nod to Sonic X in the opening cut-scene was a very nice touch. The voice acting was actually very good, I believe the lines were well delivered and the voices are close to what we have now (or what we had at least) as to not feel too jarring. The sound effects sound heavy, if that makes sense. I like it. Also, some of the mid-level voice lines are quite entertaining, and never once got on my nerves, which may be a first.

The Story:
It's good, I really like all the references in set pieces, and mentions of things that happened in older games. It gives a feeling that these stories are interconnected, which the mainline games unfortunately fail at. I can't think of the last time I played a Sonic game and actually cared about what might happen next.

The Gameplay:
I actually had a lot of fun with this, and I don't think we have ever seen a 3D fangame with this much variety, and this kind of quality and consistency in levels that were all original ideas, or old ideas with a twist. I'm going to split these levels up into sections for easier readability.

Wellspring:
A really great tutorial level. I really don't have many complaints about this one, it teaches you all of the basics in a way that isn't intrusive. My only two issues that I've had and seen other people have is with the wall of boxes, and the stairs to the right on the other side. Many people, myself included tried sliding into the boxes to break them, and then tried jumping into them which doesn't work either. It's extremely minor and knit-picky, and just slows down the pacing of the level a little. Then you get to the stairs right after it, and since they're a little bit off to the right, my eyes were drawn to the path to the left leading to a dead-end. This could be easily remedied by a trail of rings leading to the stairs to guide people in that direction. (After revisiting this, I think I might just be either dumb or oblivious...or both. But I'll still leave it here anyways)

Chao ********:
I loved this level so much. I think it's perfect the way it is. Levels that are open, but still linear fit this boost style very well.

Dragoon E-Zero (Boss):
Everything from the design, the music, the dialogue, and the boss patterns themselves were very well done I believe. That being said, it absolutely destroyed me. I like that each time you attack it, the pattern changes slightly. My problem is that some of the attacks are too quick, or don't have enough windup so that you can at least see it coming. The only way I was able to beat this was by getting lucky on the final hit. Another change I would make personally, is disabling the hurt-box while it is vulnerable. There were so many times where my homing attack would miss, and I would end up getting hit, rather than hitting it.

Area 99:
I really liked this level as well. I can't really think of anything that I feel should be changed, It has a good balance between speed and 3D platforming, both of which are set up very well. Sometimes it can be hard to tell what lasers you're able to slide under.

Wild Ridge:
This has a great foundation to be a great level, but unfortunately fell short due to awkward control and . The layout of the actual level is fine for the most part, but the controls for the Tornado are very clunky, especially in tight spaces. Once you get going and have a clear view of where you're supposed to go next, the flying is smooth. It would help as well if the characters had extended invincibility frames when colliding with walls. If you get caught in between to objects, you'll just bounce between them and it's almost instant death. The section where you have to hit the 2 targets to open the door, and backtrack a little gave me a lot of trouble. I had absolutely no clue where I was supposed to go. I don't know if I'm just bad at games or what, but I had way more trouble with this section than I should have had. The wind section was challenging, but not too difficult. It would be nice if there was some kind of UI element that tells the player which way the wind is blowing (I would imagine that the Tornado and Glider would both have some sort of instrument in them that measures this anyways). That being said, there could be interesting ways to merge that with the current UI.

Escaping the Gnarl:
Now I was not expecting that in the slightest, and I enjoyed it. I think this showed where the flying really shines. There were a couple times further into the level where the Gnarl would pop out in many places at once, and at times it can be a little difficult to see what path you're supposed to take. Now the boss itself was very creative. If you know the boss patterns and how to take it down, it isn't much of a problem at all. From what I was able to gather, it jumps out at you from the direction that you're looking in. The only problem with that is that if you're turning, you would never see it coming. Some kind of visual component would be helpful if it is coming at you from off screen, as even when using headphones, I wasn't really able to tell which direction it was coming from.

White Jungle:
This is how you rehash an old level right. I really enjoyed this one. It felt familiar yet new. Only complaint is that the camera is slightly jerky in the loop segments.

Tree Palace:
I love the concept of a large open level where you have to travel vertically like this, but it was very difficult to figure out which way you're supposed to go. There are a variety of paths which you can take, which is a good thing, don't get me wrong. But they all kinda blend together in a way where you just have to run around in circles until you figure it out. Once you get up to the platforming bit it's alright, but that first bottom section is extremely confusing. I did play the original Sonic 2020 demo version, not knowing that this was a part of a much larger project, and had the same issues there.

Waterfall Chase:
First, with the cut-scene leading up to this point, when the water starts to rush through the walls some added mist or splashing particles would go a long way in making this scene look even cooler. I had a lot of fun with this one as well. The nature of the level is very chaotic and fast, but it isn't hard at all to see where you're supposed to go. Very well made!

G.U.N Arsenal:
Very Solid level. The only thing I would consider adding is a checkpoint right before where you have to use the Chaos Dash to get up to a platform while aiming. While the tutorial prompt explains how to do it, it doesn't leave you much room for making mistakes. When I tried it the first time I launched myself straight off the ledge. In the multiple platforming sections of this level, it is possible to  chain homing attacks to make your way across easily. For some reason though, when you die, enemies do not respawn which makes this possible only on the first try. I'm not sure if this is intentional or not. Also, in the section with the sliding glass walls that you have to jump through, you can cheese it by jumping into the glass and just standing on the edge of the platform.

Moldy Jungle:
I really enjoyed this one as well, the poison spores were a great idea, and the fact that you can use Chaos Control to slow down the O2 bar was a really nice thing to find out for myself. For some reason on this level, I had a lot of issues with the mushroom bumpers either sending me too far, not far enough, or in the complete wrong direction. It seemed to be completely random, maybe tied to whether or not I was boosting when I hit them. Also, I found out that Chaos Control slows down camera controls as well, which isn't so great if you're fighting a lot of enemies that are surrounding you.

The Vortex:
I actually liked this boss a lot, though there were some issues I had with the camera, as well as the speed of the green projectiles. In this fight, you get a good view of the boss which is nice, but it is really hard to see what is on the ground on either side and behind you. Because of this, running around that back path will most likely end with you falling off and dying. When you are attacking the Vortex and he hits you into the water, you lose your rings, hit the water, and die almost instantly. Which isn't exactly fun. (Thank God there's no life counter in this game). I did manage to beat this boss due to a glitch however. From the beginning of the fight, after dying, he would just bounce up and down endlessly, wind up for an attack, then cancel out and blow me away instead. Not exactly sure what happened with that.

Various Bugs I Encountered:
I own an Oculus Rift S and upon launching the game, SteamVR launches with it. I believe it's being seen as a VR game for some reason. Maybe I'll try putting my headset on to see what happens...
The animation bug with the Vortex.
When starting a new game, I was unable to select Chapter 1 with a controller. It kept making a sound, almost sounding like it wasn't available. I had to back out of the menu and hit the buttons with the mouse instead.
Various bumpers and dash pads launching me in the wrong direction in Moldy Jungle.
In G.U.N Arsenal as shadow, I air-boosted into a wall and got launched in the opposite direction really far for some reason. I wasn't able to do it again.

To sum things up:
I really enjoyed my time with this and I'm really excited to see where this project. The point of looking at this critically as if it were a full game wasn't to just bash what you all have worked so hard on, it's because I see so much potential in Sonic Omens. And I believe given enough, time, care, and polish, this could turn out to be one of the best 3D sonic experiences available.