Question for GM regarding conspiracies

[wolffhound79]

In the last couple of years of gaming I have introduced a shadow government group into my campaigns. This group has been involved first as a tool to help directive PC towards certain areas I wanted them to go or help them out of danger. Its grown into a larger entity. First I used it to introduce the PC to a secure bunker in a area behind Mexican lines to start liberating south California from enemy hands, then used it in another to direct PCs in Guam to rescue space engineers in japan and bring them back to the US with a quick stop to a secret up link on wake island to download the technical info. Lately I've had the PCs in our New York state campaign encounter a shadowy group running around in humvees in unusual camo schemes with prototype weapons (for that time frame of 1997) securing computer resources for a yet unknown goal for a General Erickson. (They are 2 game sessions away from figuring out that general erickson is the name of a computer relay.)

Has anyone else done something like this or thrown any conspiracy into there campaigns?