QWERTY, most common keyboard set up. Make sure to also watch controlls on other keyboard set ups.
When I play a new game these day the first thing I am doing is pressing every possible key in the keyboard to see what will give a response of the game. Just about any game has a different control system and hardly any game tells you what the controls are. Should I use the arrow keys or WSAD or the numerical keys? No, they decided to go with something else for a change. So I can keep hitting all keys on my keyboard noticing I have disabled and enabled just about any effect in the game and that hardly anything works any more as it should. When making a game there are currently a few default key blocks. Either use mouse with WSAD, use arrows with Z, X and C for action keys. Do not use shift as that can cause an unexpected compatibility screen at certain PC’s. Also make sure that the left and right hand are a comfortable distance away from each other. Also make sure that the keys are easy to figure out. If you have a race game that uses the arrow keys you require no documentation but if your game has a special key to activate a special feature then make this clear to the user. A good example of this is Seiklus that actually showed an image of all keys you can use within the game and if you get additional controls it will show a new window.