By now nearly all of geekdom understands the difference between the Marvel Cinematic Universe and the Netflix shows. This is something I’ve been supportive of my entire career as a gamemaster. Here’s what I mean: There can be teams of world savers (like the Avengers) and teams of “smaller” heroes (like Daredevil and Jessica Jones) in the same world. Yes, the Avengers are in a position to stop an entire alien race from attacking the Earth. But that doesn’t make Daredevil any less fun while you watch him take on organized crime in Hell’s Kitchen.
How does this work in game? Well, one of the easiest ways I’ve found to control the action is through magic items. The world savers wind up with some pretty massive items that can do all manner of things, most importantly allowing or enhancing the largest (crowd control) spells and effects. There just is something truly epic about a fireball that wipes out an entire company of soldiers. Meanwhile, on what we’re calling the “small side”, you see things more along the lines of magic items that might enhance a sniper or a sneak thief, but you probably won’t see the same level of grand sorcery. World savers = Sorcerers. Subtle campaigns more often have necromancers and beast masters; still effective, but more in one on one fights and not taking on mobs of invading lizardmen.
The most important part is actually the mood you set. World savers have bright lights, bold colors, and (to a point) less mature plot lines. Small side campaigns are most often darker, and the conflicts are far more centered on individuals. World savers should get recognized in the streets and hailed as heroes. Small side folks may have a tiny section of the town where they are known and admired, but it will only be by those people who they have directly helped, and that number will be far smaller. But there is an upside to this. If a small side party rescues the tavern owner’s daughter from a gang of street thugs who plan to abuse her and then sell her to a slave dealer, that tavern owner will be devoted to them for life. He probably cannot afford to give them free drinks, but no matter how many years have gone by, if the party needs someone to hide them from the law, that tavern owner will risk everything to help them. Meanwhile, a year after preventing the world from being eaten by a cosmic dragon, the world savers will probably be forgotten by the public or worse seen as glory hounds.
Which you go with really depends on you and your players. Some folks just prefer one over the other. When I was running games once or twice a week, I typically had two teams going - typically one of each type. Sometimes it was fun to break out the hugely powerful team, while other times, you were just in the mood for something grittier. Crossovers don’t typically work, because the two teams are so different, that you really cannot put them up against the same types of enemies. What does work is when something needs to get done and a third party brings both teams in because they need a huge flashy unit and small stealthy one. Example - A powerful mage has summoned an army to attack the city. The flashy guys need to defend the city from the army, while the other team sneaks into the mage’s tower and assassinates him while dodging traps and a few bodyguards. While team-ups don’t work, every once in a while you can find a reason to swap one guy from one of the teams to the other, if he just seems to work better in the other style.
Never tried a small side campaign? Try one - mix it up! I think the small side campaigns really bring out the role-players on your team. This isn’t standing on hill tops watching the sun rise over a field of dead ghouls and vampires. This is getting into people lives, seeing the reality, good and especially bad, and then doing things to help these folks, because no one else seems to care. Plus - You can afford to let them lose. It may be heartbreaking to bring a daughter home on your shield, but maybe you saved her eternal soul from damnation. If the world savers fail, there goes the whole campaign world!