[NKCSS]

What Ubisoft did a few years ago with Settlers VII was to put required pieces of code in the DRM; e.g. without an internet connection, the software would not function at all; it took over a year and a lot of hard work before they found a way to write their own server to serve up the required bits, and it was just for that game, not a general solution.

[Nullabillity]

Then again, the servers were so poor that, for a long time, the game basically wouldn't function with a connection either.

[NKCSS]

True :) It was also very badly programmed, making your PC die in agony when you'd play it, even if you had the highest end stuff on the market. Still a very fun game though.