My (still incomplete) analysis of whether it's worth it for my apps...

I have some paid and freemium puzzle apps on Amazon and Play that would fit this model well, because they don't currently have ads, large numbers of people play them for free without ever buying, and the puzzles take 10+ minutes to solve and people often play for 20-30mins most days. So, this was intriguing to me.

However, as always, the devil is in the details. Some things that I haven't seen (much?) in other comments yet:

- to be accepted to Underground, you have to have an existing app on Play or Amazon.

- the submitted app must be "substantially similar to or better". I.e. no stripping out extra volumes or removing key features

- that app must not already have ads

- you have to seamlessly migrate state for players already using your game (i.e. help your current paid? users move to free (for them))

- Amazon can show ads at the end, as well as at the beginning

- you can't change your mind and withdraw the app within the first 3 months

- if you do withdraw your app, you must continue to support it for anyone who has downloaded it (including keeping backend servers running etc)

- it's not permitted to tweak your app to try and game it for extra time spent

- if your app uses subscriptions, it's not eligible

- lots of fine print here, fwiw: https://developer.amazon.com/public/support/legal/da#AmazonU...

I ran basic numbers for my apps through Amazon's convenient calculator (https://developer.amazon.com/public/solutions/underground/ca...). It's impossible to know some of outcomes, notably: how much appearing in Underground will canibalize my existing apps in either Play or Amazon?

If I niavely assume that all my usage & IAP payments switch immediately from Play & Amazon combined, to be just Amazon Underground, the numbers for one of my apps works out as:

- Number of user engaged minutes last month: 728300 (according to Flurry session tracking)

- Revenue for this app: USD$1446.37 (this is for 2 months prior, but close enough)

So, if I go to the calculator and enter 728300 minutes into Amazon, 0 mins for Google, $1446.37 Amazon revenue, $0 Google revenue, and 0% increase for both, then I get the magic number of $1457.

I.e., $10 more with Underground. But ... does this really mean anything?

On the dev/web jockey side, I figure about a day per app to adapt and submit it. Some of the steps needed for my apps are:

- rebuild the app with a different package name (presumably so it doesn't conflict with a prior installed version of my app

- ideally remove all IAP (if it is already Amazon IAP, then they'll just make it free anyway, but if it's Play, then rip it out / replace with "Unlock" instead of "Purchase" and skip the calls to Google). I have Amazon IAP already, but I'd spend a few minutes to make them all free instead. And maybe a few more minutes to remove the Amazon IAP support library. Then a few more minutes to resolve build errors. Then a few more minutes to test that I didn't screw it all up. (Repeat.)

- create a new app listing at the Amazon web site, following their carefully detailed criteria (https://developer.amazon.com/public/solutions/underground/do...)

- add an "Actually Free" sash to my icon (https://developer.amazon.com/public/solutions/underground/do...)

- build, test, repeat

TL;DR: I'm on the fence. Switching would indeed capture revenue from the 90% of users who never buy extra volumes. However, it could kill revenue from those who do. Other intangibles:

- will it annoy the customers who have paid me so far - by definition my best customers. Will they ask for refunds?

- will iOS customers demand something simlar?

- should I promote this to my customers?

- should I jump in REALLY fast (today!) so all the early Underground adopters find my apps because there will be fewer to choose from initially

For now, I'm sitting tight. I've had a strict "no ads" policy in all my apps so far (and no spyware either), so I'll see how it evolves.

One related detail: my app revenue for Android used to be evenly split between Amazon and Google Play. For the past twelve months, Amazon has been declining, even though Play (and iOS) have been gradually increasing. I'm not sure if this reflects declining Kindle Fire adoption, decreased visible of my apps in the Amazon store, or ... ?

I hope this adds some data to the commentary...