A few months ago, I put together a platformer game, planning to release it when 1.20 released and it could be used in non-preview versions. Life got in the way, and I couldn't get around to releasing it until now. The world download is attached. Feel free to customize it however you want for personal use.
As you may find if you explore the map, it uses a few relatively new commands, such as /camera and /inputpermission. These are used to make the game seem very much like a classic platformer game. A resource pack also changes several blocks to help the depth of parts of the map.
I also highly recommend rebinding your strafe right and strafe left to the left arrow and right arrow respectively. That way the left arrow key makes you go right, but appear to go left, and vice versa.
You can see a showcase on the YouTube channel, with the video linked below
https://youtu.be/cX0lyl_CfTI
Hope you enjoy!
Uses 1.20 Camera Command
Version 1.20.0.22