6 keys it is only if the game is designed for hotseat... If in future versions will add the ability to change key mapping ... If it is possible to adjust the location of the virtual buttons on the android ... If there is an opportunity to show and configure the virtual buttons of the second player on the android device .. . Then we get 6-12 push-button control (single player)... And no more limits on the 6 buttons ¯\_(ツ)_/¯ .
yes, gamepad data is stored in 16 bit integer, technically you can use BTN func with 0-15 indexes even for single player but I don't recommend to do it. What if user want to use real gamepad to play your game with 16 buttons? add another mapping for gamepads?
So, if you use BTN func with 0-7 indexes for single player game it will cover all platforms without problem I think.
Minimalism is nice, but within reason. Personally, I believe that the most optimal Number of buttons is 8. (Just like in the NES.)
You have D-pad ("4 buttons"), 2 main buttons (A,B) and 2 additional buttons (select, start).
Games are mainly used only 6 buttons (D-pad + A,B). But if you want, you have two additional buttons. You do not have need to use them, but they are.
At the moment, we have only 6 buttons on one player (Total 12). You are talking about 16 buttons ... But [id: 6,7,14,15]doesn't work at the moment (I checked). And all of my ideas about the use of the 12 keys is just a suggestion how to get around a limit of 6 buttons for a single player game for the current momnet (Of course there are problems with the gamepad. ).
P.S. What if the first player wants to play with the keyboard and the second player with the gamepad? (At the moment this is impossible)
P.P.S. Сustom Key mapping is a great thing. It doesn't matter what it is (Keyboard or a gamepad or the onscreen buttons in the smartphone). I hate when I am forced to use the "Motion Control" with my right hand, and "main buttons" left hand.