Thank you! I'm sorry to hear that it didn't work for you - I've just checked and they're still working for me, what does it show for you?
The page itself loads but the game isn't loading to a menu. When the game loads, it opens to the following screenshot with no menus:
In chrome's developer console, Unity is saying the shaders used aren't supported on the GPU: 
These shaders sound like they come from Unity's URP post processing stack, so I'm not sure why they don't work. Since it's complaining about the GPU specifically, I'm using an NVIDIA RTX 2070 Super with the latest drivers from NVIDIA (I did a clean install of the latest drivers just to be sure).
Actually, I don't think it's the shader that's doing it. I get the same shader message from chrome's development console when I play the version on the itch.io page (where the game plays correctly) as I do when playing it from one of the links. After doing some more digging, I found there is a message that only happens on the carbidefunction.co.uk links which can be seen below:
This message repeats in the console until I click into the game window, but no menu or level loads after focusing on the game window. Let me know if you need anymore information or troubleshooting on my end, I'm happy to help!
Thanks so much for all your diagnostics, really appreciate the time you've spent on this.
I think the bug lies in the UI - I ran out of time and didn't add an onscreen prompt to press R to start. While it is in the description, it's very missable, I'll make sure to add control prompts in game next time.
The messages you see are Unity trying to start playing audio in HTML5. The web standards prevent things (ads/malware) from randomly playing audio unless the user is interested in them. Only once you click on an HTML element can that element create an audio player, so Unity tries and tries again until it succeeds. I don't know what the benefit is for repeatedly trying over responding to a focus event or something similar.
Thanks again for checking everything technical for me.