The program of superdog has been made little progress, I am lazy recently.
Now I had made the level 1, it could be play but not so good.
The player could enter in the pipe world by pressing "down" key on the pipe,
and leave the world to another location of pipe.
It needs to transform the scene between the level world and pipe world,
and needs to hold the game states, so it is not easy to implement.
And then the player needs to touch the flag body as reach goal,
after the player and flag have dropped down, the program would play the
animation of pass the level, it is not hard to do that.
(To be continue...)