That'd be considered 'wrong' or missing out. Which the game tries to correct. Supposedly later levels will teach you about vim 'words' and you'll combine hjkl with lots of other commands. You cannot do that the way you use the software. How's that 'lame'?
And what kind of an attitude is this if you click on a game that is supposed to teach you about vim and complain that it's forcing you to learn something right afterwards?
That's why it's lame. You most certainly CAN. I don't care that other functions combine with hjkl in vim. They're useful but using hjkl for left/right/up/down is annoying and the restriction in this "tutorial" makes it that much worse.
It's like cheating and looking at your hands when learning to type. You'll never really learn to type properly and it slows you down a lot. Sometimes you just have to bite the bullet and do it right. I wouldn't be able to hit 80 WPM if I had to stare at my hands.