Dwarf Fortress on every machine I own.

So installed DF on my Mac my PC and my work computer for lunch time dwarfing.  I have three games on the go and I've started a couple of games over to get the start I wanted (i.e. I messed up a couple of games).   I love the Soundsense add-on for DF.  It is a very high quality soundtrack and audio track for DF that uses in game cues to trigger sounds for the game.  It is really well done.

Once I get a better grip on how the mid / late game goes (I've got my start down but I haven't really spent much time after the initial setup of my fortress) then I'd love to do a Succession Game.  The idea is that you put in 1 year in game time (really just a couple of hours of real time) and then passes the game save on to another person and they do a year and pass it on etc.  It's kind of a way of doing a multiplayer version of DF (man a MP game of DF with fortresses all over the map and raids etc. would the most epic thing ever!).

The most popular Succession Game for DF was run by the people over at something aweful.  Each player documented the journey they had and development of the fortress.  They did a really good job and it's an entertaining and epic read.

http://lparchive.org/Dwarf-Fortress-Boatmurdered/

Here's a webcomic version if you want pictures and less text lol but I really enjoy the actual forum entries listed above.

http://boatmurdered.smackjeeves.com/comics/735733/chronicles-of-boatmurdered-cover/