10 Billion Husbands is an idle game mobage, in a similar vein to games like Cookie Clicker, or Crush Crush. In the game your goal is to marry every man on earth (And then some) by submitting Marriage Registers. Think of Marriage Registers as kind of, your cookies in a sense. If you're a madman enough, you can upgrade love points so that the amount of Love Per Second (LPS) you get increases with each manual tap, though I usually just had the app running while I was sleeping or doing something else.
This is also a male counterpart to 10 Billion Wife's, but I noticed the guys in this game were much less original than the wife's, there were at least 3 Joke characters I could think up, 4 if you count the guy with a flamethrower. The CG's you get for leveling your characters high are nice, yet kind of dull looking in a way? The best CG was for Lap-Dog, but I may just think that cause Lap-Dog a cute. There is a bit of an LPS curve around either Scientist husband or Samurai Husband which makes you feel like you don't make enough LPS', at least, thinking if you're a casual player, it might take you a long time to clear. I downloaded the game on a whim and it took me 2 weeks to get every achievement, and that was with me usually running it for hours on end. I'd say for regular players it might take 2 months to beat. Also, there are in fact in game purchases to increase the rate of points you get,but it's very useless for a free idle game to have, so I didn't bother buying any. You can get free gifts randomly, or by sharing a post on twitter anyway, which will triple the amount of LPS you get per tap for a few seconds.
It does feel very lackluster in comparison to another Idle game I play, Crush Crush, but Crush Crush is more of a pseudo Idle game dating sim type game, meanwhile 10BH is strictly Idle. The guys designs were very bland or at the very least, something you see everywhere. And on the gameplay itself, it may say that it continues to rack points while outside the app, but I noticed you have to have the app open and running for it to accumulate points.
All in all, 10 Billion Husbands isn't something to write home about. If you want to kill time, you could potentially become addicted to getting all the achievements, like I did. But other than that, there's not really anything going for it. The main incentive is to do all the achievements to unlock the special illustration pretty much.