Could we get landslide... when you place dirt or (insert blockhere) it slides. This makes tunneling very hard and interesting heeh since you need to place some blocks support roof or it will collabse which is fun.

like in this very old video.
https://www.youtube.com/watch?v=6foVpJggJ5k

original landslide plugin is here (source code). It does not work with latest version minecraft.
https://github.com/HaxtorMoogle/landslide

I believe I've forked one of HaxtorMoogle's plugins before, can't recall which one. StrangeWeapons maybe?

Interesting though. If it's an existing plugin it may be better to just update that, thanks for pointing out another very interesting plugin!