You need police cars, traffic lights that zap you if you if you get to close, competing taxis, and an odd storyline like "Earl wanted to become a Blitz Programmer, so he became a taxi-driver.....". Of course, I have not yet made a game, so I have no right to say that it is lacking if these features are not included, yet it would be really fun to run away from the police, and then be a convict for the rest of the game :) .
Altogether, it looks good so far!
Altogether, it looks good so far!