THIS IS NOT A GAME!! Just use the custom block I guess, it has some events if you want custom messages. After it is done it will say if pointer lock is enabled or not. Try on https://experiments.turbowarp.org/pointerlock/1225249294/
All by me (@0znzw); I made it cause I was bored. Make sure to provide credit with a link to the project (you can also include my name if you want). The FPS can break this if you don't update the threshhold value, so make sure to update that if you use something other than 30fps.