Keeping the Pirates at Bay (2001)
gamasutra.com
gamasutra.com
If the sales figures where higher on the second game than on the first, a case could be made that the DRM used worked in transforming otherwise pirated copies into purchases. The effort spent on DRM would have been worth it (or not, if the increased sales didn't cover 2% programmer time, which is what was devoted to DRM efforts).
If the sales were more or less equal, then we could conclude that the DRM didn't affect the sales significantly; everyone who wanted to purchase the game, and could, did so. The effort spent on DRM would have been better spent somewhere else.
If the sales were less, then we might infer that early piracy actually helped increasing the sales of the game (through visibility). I doubt this was the case, but apparently it has happened with some games.
Even better, there is a very detailed post about it: http://dmweb.free.fr/?q=node/210
Critic score: 91/100 Across 51 critics ( + 14 | ~ 1 | - 0 )
User score: 8.8 Across 139 ratings ( + 127 | ~ 4 | - 8 )