Good idea for a game! the lighting is flat out amazing in your game and i think you did a very good job with it, the gameplay however seems confusing as at first i didn't understand what needed to be done, you need to guild the player into the rules and make it obvious to them how to score.
The people entering the night club could be walking a bit faster or as Spartano46 stated before freeze the sign from changing while someone is walking in, to prevent the player from being punished for a correct choice.
The music (although very loud) fit the atmosphere well and i'm pretty sure you didn't set the UI to scale with screen size as there was no UI with a resolution of 800x600px.
In the end quick little game, pretty solid mechanics and atmosphere. well done.