There really should be a tutorial level. That aside, the arrow keys don't actually work as described, unless you meant they were only for the second player. In that case, you really should have actually said that in the Help file. I'm more comfortable using the arrow keys than WASD, so that would have been nice to know going into it.
And then, of course, you take away my right-click menu and don't give me a graphics toggle in return. I have to say I'm getting really tired of creators doing that.