I have a bunch of Battle for Wesnoth (v1. campaigns that hopefully should be able to start doing this at some point during the move through v1.9 to v1.10, if the persistent worlds support via remote SQL databases feature does in fact get implemented. (It might already be implemented, the GNUniverse is large enough that I haven't revisited Wesnoth development for some time; it kind of got put on the back burner due to it's having hitherto focussed on narrating, and allowing the reliving of, historic events/timelines rather than actively changing history 'going forward'.
In the Galactic Milieu those campaigns are set in, Bitcoins are assumed to be the {inter|}galactic currency of the Hacker nation, thus the "Between the Worlds" campaign bundle is the one in which bitcoins per se will be most directly relevant to players, inasmuch as players in the Time Cadet branch of that bundle have the option of being, themselves, Hackers.
In other campaigns various variants of Bitcoin are more diretly relevant, for example in the Martian Invasion campaign, and thus in other campaigns in which the character Scotty is mentioned or involved, Martian Botcoins will probably be of more direct relevance than the original Bitcoins.
Meanwhile I have been working on http://galaxies.mygamesonline.org/ to provide another set of virtual resources tradeable for bitcoins and bitcoin-variants. The showstopper there though is not being able to compile code there, probably not being able to run there stuff that I compile at home, and then even if I can put together something that will run there it is far from clear that I would actually be permitted to run it there.
The actual Freeciv worlds on which the Wesnoth campaigns are set is are similarly hobbled by the financial hurdles involved in being able to compile and execute code on boxes that are online and that I can have incoming ports open on for people to connect to.
I also do not like the idea of putting financial stuff on servers that I do not physically control, especially not on servers physically controlled by people who are familiar with Bitcoin and its potential value.
So ultimately much of what I am working toward is probably not really going to widely reachable until such time as I can get decent bandwidth into my own physical space with control of the router. (Currently I am living in someone else's house and they control the router, allowing me only one incoming port. Thus the spawning of various IRC-bot methods of providing access to various aspects of the GNUniverse such as the Galactic Milieu and the Crossfire RPG server that inhabits that one incoming port.)
So hey, it is being worked on. How interested are you, as measured in negotiable financial instruments such as bitcoin, dollars, yen, etc?
-MarkM-