I know that for new players the learning curve can be quite steep, would it be an idea to give players either a starting kit with maybe an identified uncurse and identify scroll, or healing potions, or maybe enchanted starting weapon and armour? Once you have won and ascended you no longer receive it, the ‘are you sure you want to continue’ dialog when you start ascending can say that returning to the surface will end the starting buff.
Adding something like this would change the genre of the game. One of the whole point of Roguelikes is that your first run is the same as your 100th. If I were to ever do something like this it would be in a dedicated ‘tutorial mode’ that’s separate from the regular game.