I love the approach that showed up recently where the developer uploads their own torrent to pirate sites. The torrent has the game, but it's a slightly-modified "pirate version" rather than the regular version. You can beat any pirate group's release time, and if the modifications are subtle, people won't notice until the torrent is already entrenched. This has pretty much zero risk of punishing legit customers unless you cock up your build process and accidentally ship the "pirate version" to them somehow.

Stuff that tries to detect piracy by looking at its runtime environment or whatever is bound to go wrong, of course.