Breakdaddy sent me over an interesting article yesterday about an accountant who sat down in excel and made a fully interactive RPG. Gary Walkin designed the game; it comes complete with monsters, story lines, items and thousands of possible encounters. You can play it in most versions of excel.
It is called Arena.xlsm and you can download by hoping over to Gizmodo and downloading the game (I would upload it for download but I'm entirely too lazy for all that craziness).
post script: one can't help but wonder if Gary did this on the clock or off. He might need less free time!