Change camera resolution

how can i change camera resolution throw the game to a certain value

take a look here:

this way don’t work throw the game

The resource i showed is indeed a launcher, you can see how i have done it and implement it in your .blend/game. All the things you need are there.

You can set the Window size with the following command.

bge.render.setWindowSize(width, height)

Note: this does not effect the actual screen resolution relative to the application window.
Use a pixel post processing shader for a pixally look instead.