2) Learn to do something useful with it or at least interesting.
3) Stop worrying about hacking as there is nothing cool about it and can lead to you getting in trouble or even arrested if you hack the wrong thing.
4) If you persist on going on about hacking, do so at another site as it is obvious you are just wanting to be malicious in you hacking.
You mean reveal the exact source? Not always possible.
Disassmbling is possible, yes, but that's hard, and not every programmer's exact style.
"Modding" has come in to popular use, where a programmer or someone with access to the main source, or disassembled source, can change data, values, and code to their means and favors/advantages, or just for fun.
But in most cases you won't get too much done without knowledge on the subject.
EXTRA: If you mean hack the games over the network, that's something you should be wary of attempting.