Please note that you can still switch to ASCII-mode by pressing [g] if you do not like the graphical tiles. It also looks very funny to see how different the same areas are displayed in both modes.
I consider to allow the player to disable the extra graphics in the sidebar in case he gets distracted from it.
The white lines at the edges are not intentional and do not appear on my computer. Would be nice if you could test it with another browser or on another machine.
I went about your wish of a second high-score by awarding the medals 🥇, 🥈 and 🥉 to the players with the best dungeon-level-results.
I consider to implement your other ideas regarding leaderboards as soon as I have implemented the backend.