to vbn: This protection should have been implemented by the developers themselves. In any case, someone (even me) will have the old, unmodified exe file.
You could try encrypting the data during the game so that it cannot be read from the operating memory. This is indeed possible, but then you would likely have to change the save file format as well, to ensure that the game was played on the correct version. And this is quite a complex task.

P.S. These algorithms can always be identified by the original exe file, but reading the data during the game (as the "traffic light" does) will not be possible.