do you prefer directional keys, WASD or HJKL?
WASD is fine. But this is not The Linux Gamer's Game Jam. :P
Make the game you want to make! Weird control schemes are good if they're innovative!
Given that Linux is the Jam's target, I'd consider it good practice to make Controls rebindable (think customization, also there are probably more users that use layouts such as Dvorak, Azerty or Colemak for example.)
Also it's not that hard to do in most cases, and a big improvement in quality.
If you're anything like me, that's probably a pretty interesting read: https://en.wikipedia.org/wiki/Arrow_keys