• Movement: (arrow keys)
  For controlling character movement and menu cursor. Some selections are Up/Down (like selecting character abilities in battle.)
  
• Confirm/Jump: Z
  Your main 'OK' button. Steven also has a Double Jump.
  
• Attack/Interact/Cancel: X
  Your main 'Cancel' or 'Back' button (for menus). Allows Steven to do a roll, other characters do an attack.
  
• Cheeseburger Backpack: C
  Item, Hue, and Quest item selection.
  
• Party Screen: TAB
  The game's RPG character menu. Includes character abilities, misson, and equippable badges.
  
• Switch characters: A/D
  Swap between characters while moving around, and can tab between characters in the RPG menu (TAB).
• Game Settings/Pause: ENTER
  Opens a menu that allows you to edit settings (below), controls (screenshot above), exit and save, or resume. Can view the intro movie from the main menu (before loading a game.)
  Settings:

This is my first Steam guide, and I want to keep it pretty simple, though I have a tendency to include extraneous information. I also literally just started playing SU: AtL a few hours ago and found the menu/keyboard controls system to be rather lacking. Therefore, guide needed.

That is all.