So I first want to congratulate you! It's really cool that you could pack so many things into a game made on a week. I really liked the "glitching" effects, music, and aesthetics for the menu. The logo and menu video were really cool, were they done from scratch?
Now I will give you some of my critiques. Please don't get discouraged, I know you worked super hard on this. That's why I'm trying to be honest on my experience to give you the best feedback possible, and aid in your improvement and game-development journey! 😁
I'd say that if I had to give you a single design advice, based in playing the exploration mode and watching GoldenDonkeyProductions' gameplay video, it would be: minimize the scope, maximize the focus. What do I mean by that? Well, while it's okay to try to push yourself, you want to make your effort as efficient and impactful as possible. Personally I think that, instead of adding so many alternate realities and vehicles, that don't have that much gameplay difference between them, you should've made less but with more impact!
For example, you could've kept the basic plane, the dragon, and the futuristic one, and add different abilities for each! I'd also say that the different realities could've have better looking environments if you made the space more compact! The way that it is now, it feels a bit empty, and players probably didn't see all the cool assets. (the futuristic flying cities were super cool!) If the space was smaller rather than larger, everything would be denser, and I'd say even more fun!
The other issue that I see with the game is the performance. I want to be clear that my PC doesn't have a good graphics card, so I got a few issues because of that. My FPS was between 10-15 most of the time. The menu lagged a bit and had some stutters, tho after waiting about 3 seconds the main menu animation/video started playing correctly. I also couldn't load the survival mode, the game froze on the loading screen.
I have a few tips for remediating these kind of performance issues! First, you should try and make the game performant "as a baseline." You can do that by using many techinques, but the key is to learn to use the Unity Profiler, (maybe this video could be useful to learn a bit a about that) to know what's even causing performance issues, as well as trying to playtest on devices with low specs. (asking a friend to playtest early is really good in general, but can be specially useful for this!)
Secondly, in 3D games specifically, the graphics are usually the most taxing, so you can add settings on your menu to lower the graphical settings. The most essential, in this order, are being able to: change resolutions, exit fullscreen, change graphics levels, and disable VFX (post-processing, particles, etc.). (I think this video illustrates what I'm talking about) This will make it possible to run 3D games on almost every device, (be it without as much quality) because in case the default is not running properly, the user can lower the settings until it does.
Anyway, I think this is comment is waaay to long, but I hope is useful! (Btw, I don't know what's your native language, but mine is spanish. If your's is too, then if there's something you don't understand I have no problem in telling it to you in Español 😉)