Quoted from Hawkulous:1. You don't have to "find" the high scores etc. in the cpu, because the machine tells you all you need to know on the display!
2. Intercept the display data.
3. identify the data you want, like the high scores.
4 send the data to your pc/rpi or whatever.
This wouldn't be as easy, unfortunately.
Since the MPU generates the bitmap data for the display - that means, it gets the score, uses the font programmed into the ROM to generate how the score would look with that font and then send it to the display board - your code would neeed to be able to re-decode that bitmap display data back into raw numbers. Once you finish with one game, you'd then need to do it to games that used a different or custom font. 
