a man asked me how to find where games keep scores, eternal life or ammo. the answer is simple and I doubt is it worth to be published here or not. well, let’s try and see.as a general rule, scores are stored “as is”, I mean: if you have 666 scores, some memory cells keep [...]

http://souriz.wordpress.com/2008/05/07/eternal-life-ammo-scores-in-games/

This art has been quite developed by game hackers a long time ago. Checkout for example L. Spiro's Memory Hacking Software:

http://www.woodmann.com/collaborative/tools/Memory_Hacking_Software