I did this, we produced a board game eventually, using dice for monster spawn and dice for monster hit, and hitpoints, etc.

Pretty much nethack, but using his dungeon designs which he spent hours designing with graph paper.

I did it this way because that's how I designed my first game, on a C64, in 1986, at age 10.

He gets to design monsters, treasure, items, dungeons, etc.

Tabletop implementation is the fastest way to actually play it.