Multi-Player Games via Dropbox

A lot of us use Dropbox to synch files between computers and users. But did you know that you can also play multi-player games via Dropbox?
Back in the days of yore (meaning before the Internet made it onto the scenes, circa 1989) there used to be a prevalence of BBS (Bulletin Board Systems) around. I used to run one for WhiteGold Games. This was based on RyBBS and used to handle a lot of the necessary communications between the players of the various games that we handled. You see, WhiteGold was a Play-by-Mail company. A multi-player system where on a weekly basis people would send their games orders in by Snail Mail, we would process them through the computer, print out the results and send them back. The most common games were WhiteGold itself (a Fantasy RPG/Empire building game that was kind of free-form), StarMagic (a Space Empire game from Australia that had really huge capacity and stunning printouts), and Balance of Power (a modern warfare like, empire building game). Along with a handlful of other games this was WhiteGold primary stock in trade. I joined WhiteGold in my university Industrial Placement Year to write a new game called Robot Wars. This was a complicated games where you built up resources to build robots and program them to send them out into the world to find and destroy your neighbours.
But I digress. One of my other jobs was to use the computer to set up a bulletin board where players could dial in to upload their turns or even... play games directly. These games were known as Door games.
They mostly used ANSI graphics (they were DOS based) and had primitive functionality, but they had real game power. Players used to spend a lot of time figuring out their tactics, making (and breaking) alliances, and generally having a good time with them.
So where does Dropbox figure? Well these games didn't have network connections. They were all file based. Player lockouts were handled by separate files and data was stored in a shared system. Nothing special. Yet that methodology works very well via Dropbox. The synchronisation facility provided works very well to keep all players in the game up-to-date with what's going on.
I've tried a few games out, and though some work well, others do not. One which I have found works well is Barons.

 I now have a few trusted friends who are intent on slaughtering me. You build up your armies by taking over the surrounding towns. You tax the peasants and set you draft rate for hiring new recruits. But you can only perform a number of game commands equal to twice your level. How do you raise your level? By fighting monsters in the combat arena of course.

I am sure there are more games out there that will work successfully via Dropbox. It's just that there are so many to choose from. Let me know what games work well for you.