Note I'm angling for the Exile playbook by typing this; I'd  rather have the Action Scientist (as I'm never going to run at a con),  but I'll take what I can get.

Edge Cases
Furstwerks' Nigel Furst invented the wildly popular Gaggle to compete  with that other search engine, but when the data rolled in, the  software was--apparently on its own--flagging people, and Furst didn't  know why. Each flagged name was followed by two percentages--usually in  the teens, but some folks--politicians, known criminals, and the  like--had percentages in the early 30s.

Then there was that one guy. He had a 94/97%. And two weeks later that one guy--who was a cipher to law enforcement, a raindrop in the  rain barrel, a fly on the windscreen--killed 162 people with a 2-ton fertilizer bomb outside the Jefferson Memorial seven days after his name slid across Furst's desk.

Furst decided the percentages were important.

With some math Furst determined the percentages were a person's capacity and capability to commit what could only be called evil. Nigel Furst had invented spontaneously detecting pre-evil-sensing software. Accidentally.

No one would believe him, and even if they did, no one could do anything about it: the person hadn't done anything yet, and percentages weren't assurances. But Furst had a lot of money... and a conscience. He couldn't let these people do evil--and percentages aren't assurances, so maybe some of these people could be turned.

You do the turning. And if you don't, people get hurt.
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Edge Cases is a combination of Person of Interest and Fringe in which a group of troubleshooters investigate and neutralize potentially evil targets. Killing them is a last resort but acceptable if the problem can't be resolved any other way. PCs work in the Edge Cases department of Furstwerks, a sub-basement of a small office complex in a major metropolitan area. Missions begin as low-key investigations that metastasize into prevention of large-scale horror crises or extinction-level events. When we're between D&D 3.X this is what I run using Spycraft 2.0, as my players prefer fantasy to contemporary adventuring. But I liked Monster of the Week enough that I wanted to hack it (and, thence, Apocalypse World) for superhero gaming, and switching systems to MotW for a session wasn't that hard. My players are pros--all 40+, all gaming for 20+ years--but new to this game's core concepts.
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We'd played 2 sessions of the Edge Cases pilot using Spycraft 2.0, with Dennis as the level 6 lawman and Laura as the level 6 hacker. The MotW switch led Dennis to the Professional and Laura to the Flake, while Scott, who had missed the two-session setup, went with the Chosen.

Yes, the Chosen. We rationalized it as executive meddling wanting to shift the show's demographics, so we crammed in the 15-year-old in jeans and T-shirt with a huge magic sword made of teeth and a Great Destiny. My players adapted, and I love crap like that. It'd be like watching a show for 30 minutes and out of nowhere the show just becomes simultaneously 1000% cooler, stupider, and weirder all at once.

Anyway, the PCs linked the potential offender and his place of work--a hot lab at a local university. PCs found that potential evil scientist is working on denecrotizing human tissue. PCs bluff their way in.

Note that Dennis always wants to do this, but never plays characters that can do this, so he'll start a line of bullshit and let someone else finish it, this time, though, all the other PCs are equal to or worse at Manipulating Someone than he is, so he goes with it, finishes his line of bullshit, and is partially successful; I give them 10 minutes before the lab's gatekeepers catch on.

It's enough. I explained to Laura that magic proper doesn't exist, but the unexplainable and ridiculous and coincidental do, so if she wanted to Use Magic with that Weird +2 she had to rationalize it (a la Mage: The Ascension), and she caught on quickly, breezing through the lab's computer's security and using that data to Investigate. She learns (by cross-checking emails and so on) that the potential evil's wife who works at the lab is having an affair, the potential evil knows and hasn't confronted her, and that the potential evil is planning a confrontation... and that he has a sample of the tissue denecrotizing agent. On him. In the next lab. Where he and his wife are. Right now.

PCs rush to the next lab. The 10 minutes are up. The gatekeepers pursue them. The lab complex isn't that big, so everyone--all 15 people plus the PCs--witnesses the confrontation wherein potential evil smacks down his wife and raises the tissue denecrotizing sample in the air and is about to hurl it at her.

The players by this time had figured out that tissue denecrotizing agent was code for zombie apocalypse, and Dennis shoots the sprinkler above the potential-but-now-confirmed evil and distracts him enough to where the sample falls on the evil's head. The sample shatters. Red mist engulfs the evil. His flesh melts off and then grows back--poorly and mismatched--and while the life exits his eyes the hunger doesn't.

This is bad.

The PCs scramble. Most Act Under Pressure. Scott gets most of the lab workers to a safe room--a giant sword made of teeth is almost as persuasive as a zombie apocalypse--and Laura goes, too. Dennis, meanwhile, will have none of this and asks if he can MacGyver a Molotov cocktail out of the lab's contents.

It's that kind of game, so I say sure. He Acts Under Pressure like a boss but gets only a middlin' result to Kick Some Ass. So, while the zombie is on fire, it's also leaving. Laura notes this and Acts Under Pressure to lock down the facility with less-than-perfect results: all the doors are locked except the one zombie's heading toward. Dennis chases it down, again with only partial success. While he catches up to it, a pair of out-of-the-loop lab workers in headphones are startled by the obvious zombie and the man with a very big pursuing it; zombie munches them both, with the zombie transformation taking place almost instantly.

Scott exits the safe room, catches up with Dennis, and sees the 3 zombies. Combat ensues, and it’s messy with the sword-made-of-teeth decapitating two zombies and holes from an obscenely large handgun filling the last. However, both PCs are hit by zombie attacks while doing so.

Now, I told you, these folks are pros. After seeing how little harm the PCs could endure ("Holy crap! We only have 7 hit points? Like, ever?"), Dennis took the Medic move, and Scott took the Invincible move. So, while still infected, Dennis could do something--mechanically--about it, and went to work.

The PCs noted the college kid in the skull-and-bones T-shirt, jeans, and All-Stars outside the facility when they entered, but didn't interact with him. They regretted it now when he opened that back door the zombie was heading toward, scooped the broken sample into a backpack, and finger-shooting Dennis while Dennis rolled a 7 to Perform First Aid on Scott.

With both of them busy, Dennis alerts Laura to the escaping college kid. She books outside the facility and sees him fleeing--on his skateboard.

Remember that Use Magic rules we had? Laura uses it. She rolls and gets an in-between success. "Good thing you arranged to have campus works be working outside this area, right?" I tell her, and give her a hard choice: get the kid or get the sample. She chooses the sample as the kid skates over a hard bump and drops the backpack. The kid skates away, presumably mentally shaking his fist, and Laura stakes out the backpack, sectioning off the area with nearby traffic cones ("No way am I picking up that!").

Laura calls Edge Cases. The company sends a crew that includes hazardous materials cleanup and popup scrub tents for Dennis and Scott (whose flesh doesn't melt off and instantly regrow--but it was close).

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My players adapted quickly to the system and their characters' capabilities. All 3 come from a heavily D&D background, but very little outright baffled them. We kept track of XP, but marking it seemed to slow gameplay, and, as we were playing this essentially as a one-shot anyway, it wasn't vitally important. Dennis enjoyed the action-hero level of versatility that his character possessed, but all three were a little concerned that the game, as a whole, wasn't crunchy enough. The preponderance of Act Under Pressure rolls led directly to Dennis maxing the equivalent of Cool in my superhero hack that we played a few weeks later and made Laura a little sad that she couldn't make this move better in Edge Cases.

If I've a problem with the game, it's that Act Under Pressure contains so much information within that it becomes almost a go-to for anything that's not explicitly covered by anything else. So while I know that talking one's way past guards is Manipulate Someone and taking down the security grid is Use Magic, both could be Act Under Pressure with the right descriptions. So there's that.

As a GM, the game forced me to pay attention all the time and be on stage more than I usually am. In a rules-heavy system, I can count on the rules to tell me what happens on a failure or partial success rather than concocting something appropriate. In the future, I'll probably ask for suggestions as to what should happen rather than keeping my judgments to myself. Also, as this was my first time running an Apocalypse World-style game, I hadn't realized until I sat down to run it that I as the GM didn't roll dice. As my luck is notoriously awful, this was a great relief.

It's not worth a mechanic unless it does something.

So what do you want it to do?

Many players won't care that their heroes are hated and feared by the media or the guvment if they save the world regardless. Even being spit on by normal folks will be largely unimportant while you've still your superfriends--unless in your setting there's a mechanical reason they should care.

Does your setting--maybe a Silver Age one--care? Are there rules for isolation and distance from humanity? Do powers wane if the cheering stops? If the only downside to a bad rep is entities refusing to help the heroes, that's just a campaign switch the players have turned off, and then they can ignore it and solve problems another way and never worry about the reputation problem again.

"We're outsiders now," the players will declare. And that whole maintain-your-rep mini-game just ends. Arguably, now there are more opportunities for conflict--with the good guys!--than before, and in a superhero game, that's sort of awesome. You get to fight SHIELD and Hydra! Kobra and the Justice League! Bring it!

And if the GM just kills them with the Big Goods, then A) why haven't the Big Goods righted all the world's wrongs before moving on to Our Heroes? and B) the campaign ends.

So, yeah, why care? What does caring about one's reputation bring to the table?

Revenge.

I'm thinking of some kind of scaling mechanism, where super attacks against "normals" automatically do +1 harm, and normal attacks against supers automatically do -1.  And something like stat+3 for a normal is +0 for a super.

My hack's working like this: PCs start with a 10-harm box meter that gets filled as they take harm and you can get more boxes from powers and moves, but NPCs get a meter that's anywhere from 1 box long (for a bunny or bystander) to [number of PCs] x20 for giant robots, world conquering villains, and kaiju.

That was just easier than trying to fit both the Hulk and Batman on the really small clock that AW uses.

And Chan: Is that in-playtest version circulating online at all? I dig the random power assignment concept.

No, I've a few week's worth of work before I'm ready to smack it on the ass and send it into the world, but thanks for the interest.

The random power generation thing is actually pretty easy if you want to swipe it though. Just put powers in card sleeves and deal 'em. I mean, there's more to it than that, but the idea's pretty basic. I used cards for several reasons the game itself'll make clear, though.

The writing has to be pretty tight to fit on the cards, so the game's powers look like this:

Control Electricity

• Control Electricity: When you want electricity to obey you, select the followup move, pick A, and Empower. On a miss, it doesn’t, can’t, or misunderstands. On a hit+, it does and make the followup move. If improved, take +1 forward. List A: Issue the command ? silently to some electricity in the area ? verbally to all electricity in the area.
  
• Attack: Keep 1 better weapon; it takes the electricity tag. If improved, repeat.