I’ve no idea how they even discover this stuff, but someone’s realised you can unlock five of SNK’s XBLA games with a Modern Warfare 2 glitch, using either the game itself (which really reliable statistics show 99.9% of Xbox 360 owners already have) or the demo (for the other two people).
So for whatever reason, running Modern Warfare 2 and launching the games from inside it apparently tricks your system into temporarily authorising the XBLA trial versions into full versions of Garou: Mark of the Wolves, The King of Fighters ’98 Ultimate Match, Metal Slug 3, Metal Slug XX, and Samurai Shodown II. Only those games, though. For whatever other reason.
Since pretty much the entire internet knows by now, it’s a safe bet a crack squad of nerds over at SNK and/or Activision is already on the patch job, so enjoy your free games while you still can.