Selecting good, non-conflicting keybindings for a game

Question

PC keyboards weren't designed for gaming, compromises were made to bring the price down, so some problems occur. Most importantly, when you hold down certain keycombos, some keys don't react to pressing.

My game has two users at the same PC control two characters in realtime (i.e. not turn based). An instance of the problem: player 1 holds Up and Left to go in that diagonal direction. Player 2 is then unable to go to the right (with "D"). Beyond being merely annoying, it can give an unfair advantage to a player who opts to use the bug as a cheat. Not fun :(

The basic commands are: shooting, walking left and right, and jumping. Shooting is done with LeftControl and RightControl, which don't conflict with anything, so let's consider only the movement keys.

On my laptop, most obvious keybinding combinations fail:

• WAD and arrow keys fails with Up+Left+S and Up+Left+D
• IJL and arrow keys fails with Down+Right+J (though Down is technically unused, a player often holds it down anyway)
• arrow keys and numpad keys fail with Down+Left+NumpadLeft
• all-letter combos like WAD and IJL tend to work, but I don't like leaving the arrowkeys unused, and crowding the users' hands together.

Is there a website that list statistics of common supported keycombos on various keyboards, to help me make my decision for defaults? (they're configurable, but defaults matter.) I seem to recall a relevant site called keyboardssuck.com, but I can't find it now.

How have you dealt with this problem? Just ignored it?

Does the problem depend on the OS, the API, the mobo? On anything else? I think it only depends on the keyboard model, but gotta ask.

edit: Now I know what this is called: "rollover"

Answer 1

This is a hardware-implementation issue. To me this problem presented itself as depending on how the keyboard is wired internally.

To me it seemed to be like theres no real standard to this. A certain combination of 4 keys at the same time worked fine on one computer (a desktop-machine) - another keyboard simply could recognize no more than 3 of those. (laptop)

My hunch is that you can rely on all of the control-keys (ctrl,alt,shift,windows,apple-keys) because they are probably wired on another "layer". But when it comes to "normal" keys including cursor keys, numpad keys and the likes, i would say that you can probably rely on 3 keys at the same time.

Answer 2

The best bet is probably to let the user choose his own keybindings.