Hello Sir,
I am an expert HTML5 Game Developer and I developed many Online Games including some Facebook/Messenger games (FB Instant Games).
I can develop games within the shortest possible time maintaining the best quality. So, if the game is short, it can take 3-5 days including planning, asset preparation, development, and testing. If the game is quite big it can take 7days to 1 month based on complexity and size.
Price is negotiable and also varies based on game complexity, assets and time required for the game.
Please give some hint or description of your game so that I can give you exact price and time.
For my previous games & further discussion, please initiate the chat.
Best Regards,
Sazzad