Thank you for the very detailed explanation Lone Spelunker. Good idea to have the different predefined keysets to choose from. I will see if I could implement this during the next weekend. What could a possible alternative to the numpad look like. Do you think [q], [w], [e], [a], [d], [z], [x], [c] could be a proper choice? I do not want [s] to skip a turn since a lot of people are use to the [w], [a], [s], [d] controls and therefore would accidentally skip a turn when they want to move southwards. So my choice for skipping a turn would still be [.] as for the vi-keys.
Since my game is playable in browser, I cannot provide two different downloads in order to keep the original 7DRL-version. So I think I will need to host a second game page for the updated game and link to it from the original 7DRL-game-page.