Snake Game in Flash

Hi

A client of mine ask me for a flash game like Snake. Here is a link of something that looks and work similar: http://www.1pagedesign.com/games/flash_snake/flash_snake.php#game_code

Hi would like to ask to the community:

1 - some ideas on how to build this. I build flash sites with AS3 but I’ve never built any game.

2 - how much should I ask my client to do this job.

Thanks