Zombie Outbreak Simulator for iOS Update Released!

Hi everyone,

Apple approved the update for ZOS on iOS, so it’s now available on the store. Woohoo!!

ZOS for iOS update now available

You can get the free version of Zombie Outbreak Simulator for iOS (free to download and try out, with in-app purchases to upgrade), or if you’re sure you want everything you can go straight for the paid version.

So, what next? Bugs, that’s what :| I’m seeing some crashes on the Android version that I need to take a look at…


ZOS for iOS: Update Submitted to Apple!

In my last post on the ZOS for iOS update I had all the maps, all the actions (bombs, soldiers, helicopters), and all the usual zombie mayhem all working. So it was “almost” ready, right?

Well, not quite. There were a whole bunch of tedious things left to do – like the tutorial, credits, sharing, purchases, ads, crash reporting, analytics, debugging, and fixing featured maps. Plus random issues with the Android version that I had to jump over and fix in the meantime. That’s why it’s been over two months!

However, I have now finally finished, woohoo!!! I’ve just submitted the update to Apple for them to review.

ZOS for iOS update waiting for review

Pretty soon those old app icons will be no more – the update uses the new icon from the Android version.

New ZOS for iOS icon

Now I just have to wait for Apple… hopefully I have better luck with the review process than back in 2012! :)



ZOS for iOS: Player Maps Beta

Hi everyone,

I’ve just released the third beta for the Zombie Outbreak Simulator for iOS update that I’m currently working on. This version includes the ability to play on any of the over 2,500 player maps created at www.class3outbreak.com.

ZOS for iOS update with player maps

There’ll be a few more beta releases before the game is ready for a full release, so there’s still time to sign up to help beta test if you’d like to. Just fill out this form and I’ll send you an invitation within a few days. If you’ve already signed up and haven’t received your invitation, let me know.


ZOS for iOS: Beta Testing Started!

Hi everyone,

Apple has approved my first beta of the Zombie Outbreak Simulator update for iOS! I’ve just sent out invitations to the 60 people who’ve signed up for testing so far.

ZOS for iOS update ready for testing

This is only the first round of beta testing – I’ll be releasing more updates to the beta testers as I complete them. In particular this first version has no sound or music yet (that’ll be in the next update), player maps, tutorial, and a bunch of other things.

There’s still time to sign up to help beta test if you’d like to, just fill out this form and I’ll send you an invitation within a few days. If you’ve already signed up and haven’t received your invitation, let me know.


Zombie Outbreak Simulator Hits One Million Downloads!

A few days ago Zombie Outbreak Simulator reached one million downloads on iOS and Android!!

Zombie Outbreak Simulator downloads

ZOS was released on iOS in April 2012, and has now been downloaded by 373,000 people across both the paid and free versions.

ZOS was released on Android in November 2014. It overtook iOS in March 2016, during its highest month for downloads due (I think) to The Walking Dead TV show. It’s now been downloaded by 627,000 people.

ZOS for iOS now has some catching up to do! :) I’m working now on an update to ZOS for iOS, to finally bring all the new stuff we added to ZOS for Android back to iOS.


ZOS for iOS: Call for Beta Testers!

Hi everyone,

The long-awaited update to Zombie Outbreak Simulator for iOS is well underway! I now have all the core gameplay features ported to the new cross-platform project that I’m building for both iOS and Android.

ZOS for iOS on multiple devices

There’s still lots more to do before it’ll be ready for a full release. However, I’m at the stage now where I can start some very early beta testing in the next week or two.

If you’d like to help me beta test the update, please fill in this form. I’ll be in contact when I’m ready to start testing.



ZOS for Android: Making it More Free to Play

Zombie Outbreak Simulator (ZOS) for Android was released in November 2014. Since then it’s been downloaded by over 550,000 people.

Feedback on the game has been very mixed. Although a lot of people really love it, there are also a lot of people who really hate it.

ZOS for Android ratings November 2014 to June 2016

Although the tutorial update that I released at the end of December 2014 helped improve the ratings (from about 2.9 stars to about 3.5 stars), there’s still a high percentage of 1-star ratings coming in every month.

ZOS for Anroid ratings graph November 2014 to May 2016

The vast majority of the negative feedback received now is about the in-app purchases and pricing.

With most free-to-play games there’s some kind of progression. Through playing the game you earn something, like coins, gems, points, whatever. In the game you can spend these credits to keep progressing with the game. You can keep playing for free more-or-less forever, although it gets harder. Or, if you want to you can spend real money on an in-app purchase to buy something extra, like more credits or extra items, which help you in the game.

The problem with ZOS is that it’s not like this. There’s no progression of game play, instead it’s more of a toy that you can tinker with and see what happens. It’s up to you whether you supercharge the zombies to make them win, or the humans to make them win. You can choose whether to use the bombs, soldiers and helicopters to help the humans, or not. There’s no way to reward you for winning (you can’t win!), and there’s no progression between games. So the usual free-to-play approach for in-app purchases doesn’t work.

So, the approach I used was more of a free trial. There is limited functionality available for free – a couple of maps, limited settings, a couple of bombs / soldiers / helicopters per game. The idea is that this is enough to get a feel for what the game is like. If you like the game, then you can pay to unlock the full game (or just parts of it). Separate features cost from 99c, up to $4.99 for everything. I think this is better than entirely paid-up-front, because this gives you a chance to try it out first.

Unfortunately, a lot of people hate this…

ZOS for Android one star reviews on purchases

So, for some time I had been thinking about how to let people keep playing for free, rather than hit the limit of the free features and get annoyed. The most obvious choice was some kind of rewarded video – temporarily unlocking part of the game by watching an ad. People could then either keep playing for free by watching ads, or choose to pay to upgrade if they got tired of the ads.

Coincidentally, in early January of this year I was contacted by AppGrade, offering their platform for rewarded videos. After some discussions with them I decided to give it a try.

On the 18th of February I released an update which added the ability to watch a video to get extra bombs, soldiers and helicopters (10 of each), in addition to the existing options to purchase. I’d decided to trial video ads with just the bombs / soldiers / helicopters first, to see how it went. That way if it didn’t work out, I wouldn’t have wasted too much effort on it.

ZOS for Android - watch a video for bombs, soldiers, helicopters

The response to the video ads has been good. Soon after release there was a dip in revenue from purchases. I suspected this might happen, as people who previously felt ‘forced’ into buying an upgrade, might have decided to watch ads instead. However the revenue soon picked back up again, back to around its previous levels. And the ads themselves have brought in some extra revenue on top of that. (This chart is in USD).

ZOS for Android revenue when adding rewarded video ads

One statistic that I thought was most interesting was that there was an immediate increase in the amount of time people played the game per session. Before the update sessions averaged around 7 to 8 minutes, after they averaged around 8 to 10 minutes. For reference I’ve coloured the Sundays in red (there’s always a dip in session time every Monday).

ZOS for Android average session time with rewarded videos update

Unfortunately, the update didn’t do anything to improve the ratings :|

ZOS for Android ratings after adding rewarded videos

However, I still think it’s been a worthwhile update, and so I’m planning on making more features of ZOS for Android free by unlocking them with rewarded videos.

At the moment I’m working on an update to be able to unlock the settings (in parallel with working on the iOS update). And then after that I plan to add the ability to unlock the online and offline maps (the player maps will stay as a paid feature).

My goal is to complete both of these free-with-videos unlock features before the ZOS for iOS update is complete. The paid version of ZOS for iOS will of course have everything unlocked in the original download. However the free version of ZOS for iOS will have the same purchase and video unlocks as ZOS for Android, and so I want to make sure I get it ‘right’ on Android before releasing the update on iOS.


ZOS for iOS: Update started!

Zombie Outbreak Simulator on Nexus 5X and iPhone 6s Plus

TL;DR: Development of the ZOS for iOS update has finally started! Details below…

Hi everyone,

Zombie Outbreak Simulator (ZOS) for iOS was first released in April 2012. A few updates followed, but the last update was way back in May 2013.

Focus then shifted to Android when in late 2013 I received funding to make an Android version of ZOS. ZOS for Android was released in November 2014, and I’ve made a few updates to it since, but most have been minor things like adding a tutorial, or bug fixes of various kinds.

The Android version of ZOS included some new features over the iOS version (soldiers, helicopters, player maps, and an entirely new UI). Ever since the first Android release the plan has been to port all of the new stuff back to iOS, however during 2015 I was too busy to get around to it. A couple of months ago I posted a sales update for ZOS on Android, and mentioned that I was finally in a position where I could get back to the iOS update.

For a while now I’ve been tinkering with how exactly I was going to update the iOS version. The core of ZOS for iOS was developed during 2011 to 2012, eons ago. The core of ZOS for Android was developed in 2014, and even that’s ages ago in mobile app development time-frames. Some of the factors I had to consider were:

  • The core game of ZOS for iOS was developed with C++ and OpenGL. However the UI and interaction with Google Maps was developed with Apple-specific Objective-C and UIKit.
  • When developing ZOS for Android, I was able to port over the C++ and OpenGL without too much effort. However the UI had to be completely rebuilt from scratch. We used the cross-platform Cocos2d-x to do this. However then a bunch of Android-specific Java code was added, to interact with Google Maps and other utilities. And then on top of that I added the new features like soldiers, helicopters and player maps.
  • ZOS for iOS was originally designed to work with iOS version 4.0. We’re now at iOS version 9.3 – that’s how old ZOS for iOS is!
  • ZOS for Android was built with Cocos2d-x version 2.2.2, which was released in December 2013. It’s now at version 3.11.
  • ZOS for Android was built with the Eclipse ADT (Android Developer Tools), the best option at the time. Google discontinued support for this in June 2015 – now Android Studio is the recommended development tool.

So some of my options:

  • I could grab the C++ and OpenGL code for the soldiers, helicopters and player maps from ZOS on Android and merge it back into the old ZOS for iOS code base. But then how do I fit the buttons / screens / etc for those features back into the old iOS UI?
  • I could grab all of the current version of ZOS for Android, which includes a UI built on the cross-platform Cocos2d-x, and port that back to iOS. But this is using a version of Cocos2d-x which is already 2.5 years old.
  • How much longer will I be able to keep developing ZOS for Android with Eclipse, before I’ll be forced to update to Android Studio anyway? I already got hit a few months ago where one small update rippled through to needing updates to 3 other components. How long until this falls apart?

In the end I decided to start over from scratch! I’m creating a brand new project with the latest version of Cocos2d-x (version 3.11). On Android I’m using the latest Android Studio 2.2 (an early release version which Google just released 9 days ago with new better support for Cocos2d-x development). And on iOS I’ll be building a new app designed from scratch to work with the latest devices and version of iOS.

Most of the core game and UI code in ZOS for Android should be able to be ported over to the new app, with a few tweaks here and there due to changes in Cocos2d-x. The major new work will be in separating off the Android-specific parts and implementing the equivalent on iOS. For most of this I’ll be able to grab bits and pieces from the old ZOS on iOS.

One major advantage of building a new app is that I’ll now have both iOS and Android running from the one set of code. This means any new updates in the future will automatically work on both platforms. No more cases where there’s a 2 year delay converting from one to the other! This is why people use cross-platform games libraries like Cocos2d-x or Unity in the first place. Unfortunately way back when I started ZOS for iOS this wasn’t an option, due to the integration I required with Google Maps at the time.

So to get to the point of this post: Now that I’ve figured out the how, I’ve finally started! The photo at the top of this post shows the new app, with the same home screen from the same code, running on both an Android Nexus 5X, and an iPhone 6s Plus!

The next question of course is “when will the iOS version be ready?” It’s too early for any kind of estimate at this stage, but at least I’m working on it! :D



ZOS for Android: Ten Thousand Devices


I first started development of Zombie Outbreak Simulator for iOS back in mid-2011. At the time I bought an iPhone 4 (released about 6 months earlier), and an iPad 2 (released a couple of months earlier), to use for development and testing. Later during development I bought a second hand iPad 1, and a reconditioned 3rd generation iPod touch (which was basically the same hardware as an iPhone 3GS), to use for more testing.

This meant that with only 4 devices, I had basically every possible combination of hardware which the game could run on (the two older-generation iPhones from 2007 and 2008 were incompatible as they were too slow). When I released the game I could therefore be quite sure that it would work for everyone.

Of course now there are more iOS devices, but it’s still only a handful. There’s only 8 current plus 11 discontinued-but-still-supported iOS devices across the iPhone, iPod, iPad, iPad mini and iPad Pro.

In contrast there are literally thousands of different Android devices out there. When I first started beta testing ZOS on Android in mid 2014, there were over 4000 Android devices compatible with ZOS.

Recently I noticed that there are now over 10,000 devices compatible with ZOS!


So what does this mean? It means that although I’ve developed and tested ZOS for Android on a bunch of different devices, it’s impossible for me to test on all of them. And that inevitably means there’ll be bugs :( Usually obscure ones which only show up on a handful of devices.

For example, recently some people were reporting a crash on startup. This seemed to be happening on the Sony Xperia M4 Aqua consistently, but also on a few other devices.

ZOS for Android crash reports

Many thanks to Darren who was able to help me out by connecting his phone to a computer to get the log messages from the crash. I was able to track down the problem to an obscure bug in Android which only occurs in this situation:

  • On Android 5.0 (Lollipop), and
  • With a 64 bit CPU, and
  • When using SQLite (a database library I’m using), and
  • When storing the database outside the app folder

Google fixed this bug in Android 5.1 (Lollipop MR1), but that didn’t help anyone still on 5.0.

Luckily there was a workaround I could use to avoid the problem, and I released an update a few weeks ago which seems to have fixed the crashes for people.

Now it seems a new bug has surfaced – a few people have reported that the online and player maps just stay grey without ever loading any of the map images. So this is my next challenge to try to figure out :)

ZOS for Android missing map tiles

If you’re having any issues with ZOS on Android, get in contact and I’ll see what I can do to help.


ZOS for Android: “The Walking Dead” Effect?

A couple of months ago I posted about sales for ZOS on Android, and I noted that sales had jumped a lot in October last year.

ZOS for Android sales November 2014 to February 2016

At the time I theorized that this was because the latest season of The Walking Dead started airing in October.

The Walking Dead airing dates

At the time I wondered if there’d be a drop in players when the season finished.

Well, it looks like there was! Here’s the number of players per day for a while before and after the final airing date on Sunday the 3rd of April:

ZOS for Android players per day for March and April 2016

For reference I’ve coloured the Sundays in red. The number of players generally peaks over the weekend, dropping during the week. However after the season finale of The Walking Dead there was an immediate larger-than-normal drop, and during the following week the number of players dropped to the lowest point it had been in over a month.

Sales peaked at their highest ever in March, were slightly less in April, and so far are looking to be a bit lower again in May.

I wonder if other zombie games have seen a similar effect from the TV show?

If anything, this tells me that I really need to get the updated version of ZOS for iOS done well before the next season starts (presumably October 2016). I’ve started on it, but it’s very early days yet.