Lol... honestly, I had never played Robotron much... and hiding joysticks at work may be hard to get away with...
I have never played it before, except for testing if it works, but still I wouldn't even think of playing something that requires diagonals using a keyboard. You even up the ante by trying to play a game that uses two control devices, so you even have to do the diagonals with the weak hand, too
Just smuggle a gamepad to work, it is worth the risk
Also, it'll do wonders for your blood pressure