The same people who make "Zombies, Run!" have a superhero-themed bodyweight workout app that finally came out on Android last week. I've downloaded it and done the first mission. So far: has some minor issues, but fun and definitely likely to make me do more situps.
Initial thoughts:
* The superhero theme is very well executed. You're testing the (government's?) new battle suit to repel the alien invaders, and you can do both training and story missions with a variety of different body-weight exercises. The voice acting is delightful. I do find that since I'm moving around so much and jumping and thus making a fair amount of noise myself, I can't always hear the narration. And because there are so many different things to do, the exercise you're doing only sometimes makes much sense for what your character is doing. But it's still a lot of fun.
* Unlike things like that "you are your own gym" book, it really truly doesn't need equipment. It needs a wall, a chair, and a you*2you sized rectanglular prism of free space. The chair could even be a sturdy box or something, especially if you're like me and can't step up on a full-sized chair that many times in a row.
* This is really sort of a mixed blessing -- the motion sensing is not nearly as advanced as you might think if you just read the description, which I suppose I really should have known beforehand, since this would be making way more headlines if it could do what it sort of sounds like it can. Anyway, it's just general motion sensing, which means it tracks repetitions, not always terribly accurately. But, what this means is that it doesn't matter that I have the upper body strength of a banana -- I can do pushups off a wall or table and it still tracks them because it doesn't actually have any idea what you're doing. This would be a drawback for Serious Athletes, but if what you want is imaginary story points to encourage you do work out more, vaguely-accurate rep and calorie tracking does the job just fine. You could also probably just sit there and wave your hand at it but...why? I mean, the story's not that exciting. ;-)
* You can tap the device to pause it at any time, which is great if you need a drink break or take longer than 10 seconds to find the right place for your phone to track or whatever. As with Zombies Run missions, you can stop the mission and restart from the same place later if the workouts are too long for your fitness level or you just suddenly realize you have to go do something else now. And if there's an exercise you can't do, you can skip it with no penalty other than potentially missing story content. There is not, however, much in the way of customization, so this is probably not worth it for people who just can't do a substantial number of the exercises and don't feel like subbing in other things.
* You have to keep moving your device around to find the right place for the camera to track different activities, which is kind of unavoidable given the mechanic, but is mildly annoying. I should get one of those little phone stand things. The annoyance factor would be mitigated significantly if they added some sort of "suit calibration" mode where you could just do the exercise a few times to check placement and tracking (and as an added bonus, also learn how to do any unfamiliar exercises).
* In addition to the peppy superhero music and narration, it has a little grid-outline guy doing the exercises. 6 To Start is generally very good on the gender front, so this is more of a suggestion for future updates than a complaint, but it would be nice if they had a female figure option. Or even a more blocky, "robot" figure which would be both conveniently androgynous and fit the theme nicely.