Less Is More...Is Less
Usually when I start world building for a Supers game, I get to thinking about the other superheroes in the world other than the PCs. Marvel and DC have hundreds of Superhero characters and so do I, so I want the PCs to meet them. Also, other heroes round out the setting and make it feel like you live in a universe.
Unfortunately this can backfire on me. If the PCs are in big trouble they are going to call for reinforcements. Sure the other heroes could be busy but all of them? Think about the Avengers or the Justice League. Not only do they have a dozen or more active members, they are on pretty good terms with the vast majority of the major and minor heroes of their respective universes. If someone drops an Infinite Crisis or Secret War in their laps you can be pretty darn sure everyone from Animal Man and the Teen Titans to Nova to Fantastic Four are getting a phone call.
So when running my current Champions game, it's been quite an effort on my part not to create lots of NPC heroes. A low number of super powered individuals worldwide and a lack of Superheroes compared to Supervillains (Villains outnumber heroes roughly three to one in this setting) creates a very interesting dynamic that has made this game feel quite different from many of the other superhero campaigns I've run. Each hero is more important. Keeping yourself and every one of your allies alive (since the setting is also a tad more deadly then the standard 4-Color Comic Book milieu) is a priority no matter what else is going on.
In the case of our current situation, what do you do when most of your heavy hitters are out of energy/Endurance, the rest are at half power, every body is pretty fatigued and you just found out the mystery villain who set recent troubles in motion is about to show up at location X. I mean, the look on the players faces was awesome. There was this heroic and self sacrificing need to go forward, to nab that bad guy, knowing full well they don't really have the strength to do so. Fantastic.
How do you handle it? Is your Supers universe teeming with heroes or are the players the only game in town? Something inbetween? How does it effect the challenges in the game?
Really curious to see some responses to this.