Small game that can be re skinned later

General information for the business: just a small simple game
Kind of development: New program from scratch
Description of every module: looking for someone to build a small demo game. i need to have the ability to change the graphics.
i don't really mind what type of game builder program is used but must be able to place it in a web page without additional software.

The idea is so i can use it as a template for building variations of the game. This should then help me demonstrate the concept of changing graphics changes the meaning of a game and people's reactions to it.
i will have graphic variations from cute to very violent and collect user statistics.
Description of requirements/functionality: Bomber type. so.....simple side scrolling
plane controlled by arrow keys flying past scrolling background occasionally dodging stationary objects in the sky.
when "space" is pressed it will drop a "bomb" onto the ground. with small explosion when it hits
would like the game to slowly increase in speed or difficulty.
three types of objects on the ground randomly placed
good object hit score increases by 1
bad object hit lose a life (3 lives)
random non scoring items like a tree or rock

end when all lives are lost. replay and high score.
possibly a few other random non scoring items on ground.
very simple.
Extra notes: here is a very very basic sketch. the objects should be big enough to be able to change the graphic from say a soldier to a civilian or an animal