Participating the Razor Puzzle Beta is easy. But:
Your device must be running at least iOS 17.5 (Apple devices, only, no support for Android).
iPad is preferred if you own one. You need the larger screen to fully enjoy the app. However, it will run on phones too and I am interested in feedback from phone users.
Now switch to the device on which you will install Razor Puzzle and view this page there.
Then:
If you already have the Apple app called TestFlight installed, just click on the following link
https://testflight.apple.com/join/XSYVAKUf
and the install should proceed as you follow the brief instructions. You will have TestFlight if you have previously participated in betas on the device. That's it!
If you do not already have TestFlight installed, or your version of it is too old, you also click on the very same link
https://testflight.apple.com/join/XSYVAKUf
but it will offer the opportunity to install TestFlight first. The page will also have a second action (you may have to scroll to it) for installing Razor Puzzle.
After you have installed TestFlight, don't open it directly (even if you are offered the opportunity to do so from the app store download). Instead,
If you can still see the action for installing Razor Puzzle
Use it to open TestFlight and complete the install.
If you can no longer see the action for installing Razor Puzzle
just click https://testflight.apple.com/join/XSYVAKUf again to complete the install.