http://armorgames.com/play/12546/the-last-castle
Since it has a chance to ruin the gameplay for you, click the spoiler button if you REALLY want to hack (wow, I feel stupid now that I just typed that in on a hacking site).
Experience is 4byte * 1.
I'm pretty sure you can manage the rest of the game from there.
Also, it IS true that wave 31+ is easy as pie.