Apologies for this wall of text :)

I've started work on a new backend for War Worlds, which I'm hoping will solve a number of problems in one swoop. The biggest issue that I am facing at the moment, other than regular bugs and so on, is the fact that the game costs quite a lot to host on App Engine. When War Worlds first started, and for the first few months, hosting was quite cheap and while income from ads & in-app purchases still wasn't quite covering the whole costs, it was manageable. But over the last week or so, there's been an influx of players (which is a great thing!) and costs have skyrocketed to $20-30 per day. It's not exactly breaking the bank, and there's no danger of me going broke just yet, but for the number daily active users (for the record, about 500) and QPS (2-3) I'm doing, that's about an order of magnitude more than I would like to be paying.

Around half my costs go to App Engine's "frontend instance hours", with most of the other half going to datastore reads. I already make quite heavy use of memcache, to reduce the amount of datastore reads required, but the nature of the game is that things are largely not static, which naturally limits the amount of benefit you can get from heavy caching.

So I have begun work on re-writing the backend. Instead of Python, this time it will be in Java, and I plan to host it on something other than App Engine (I haven't decided exactly what yet, but I am thinking of using EC2). With this, I'm hoping to solve a couple of problems in one fell swoop:

1. By using the Java on both the client and server, I hope to be able to share a lot of code. Currently, the logic to simulate stars lives mostly on the server, but some if it was re-written in Java so that the client can do it as well. However, we've been plagued with a few out-of-sync conditions because the client-side prediction is not perfect. By having both client and server in Java, I should be able to make the client-side prediction much more accurate which will hopefully make these issues a thing of the past.
2. I will be able to switch data stores (I haven't decided yet if I'll stick with a key/value-like store or switch entirely to relational) but App Engine's consistency gaurantees are extremely strong (probably stronger than I need) and it causes write performance to suffer -- in a fairly dynamic world like War Worlds, that makes performance overall suffer.
3. The infrastructure needed for a "smooth" transition to a new backend will pave the way for supporting multiple "realms" in the future.

Client-side prediction

One of the biggest performance improvements I've made to the game over the last couple of weeks involved moving a bunch of logic from the server to the client. Actually, the server still performs all the same logic as before, but the client no longer needs to wait for the server to complete it, since it can run a lot of the simulation itself.

However, because the server is currently written in Python and the client in Java, it means I basically had to translate the algorithm and I have two version of the simulation that I need to maintain in parallel. This has caused a few issues already where the client thinks one thing and the server thinks another, and these are quite subtle issues to solve.

So by moving the server to Java, I hope to be able to share the exact same code between client & server and these issues should disappear. This will also allow for more advanced prediction on the client (so like in the "Build Confirm" dialog, the expected build times are woefully inaccurate, but with the full simulation available on the client, I'll be able to make those numbers accurate).

Different Data Store

The other concern for performance has been the write speed of the App Engine data store. The App Engine datastore provides strong consistency gaurantees, but it does so at the expense of write performance. Writes to the data store typically take 100ms or so, which is huge. I've tried to structure the application as much as possible to reduce the number of writes per request, and for the most part things perform reasonably well. But there are certain requests which simply take far too long to complete (collecting taxes from all of your colonies is the most pertinent example).

As I said above, I haven't decided yet whether I will stick with a key/value style of data store, or whether I'll go for a full relational data store. They both have their pros and cons, but one thing is for sure: which ever I choose, the performance is definitely going to be better than App Engine's.

Additional Realms

I kind of like the idea that everybody is in the same universe together. It makes the game feel more expansive. But a couple of things have come to my attention that make me think that multiple "realms", that are separated off from each other, might not be an entirely bad idea.

The first is the multi-lingual issue. For a while, we only had English-speaking players in the game. But there's been a lot of new non-English speaking players join, and I've noticed some... shall we say, "tension" between the two groups. I hate the idea of "racial segregation", and I would have loved for everyone to just "get along" (and I do plan on adding language-based filters to the chat), but I also think it might also be good to have language-specific realms. This would also allow for cool things like star names in your native language (assuming I can get the random name generation algorithm ported to other languages), which would be quite neat.

Also, additional realms could allow for things like realms with slightly different rules, realms with particular end-game scenarios (vs. realms where this is no "end-game" as such and you just continue expanding forever) and so on.

Conclusion

In any event, what you will see is that in the next couple of weeks, there will be an update to the game which will allow you to join the "Alpha" realm or the "Beta" realm. The "Alpha" realm will be the App Engine backend that you're all familiar with today. The "Beta" realm will be the new backend. Eventually, the "Alpha" realm will be switched off (hopefully not before everyone has volunterally moved to the "Beta" realm because it's going to be so much more awesome!) and all new development will continue with the new backend.

In the meantime, I will continue to update the game and fix bugs, but I think it's important to get this transition done as quickly as possible so that I'm adding features and bug fixes to both versions for as short a time as possible.

Please send me your comments and feedback on this change (leave a comment below, post to our Google+ community, or send me an email directly)

I added a seemingly fairly small change to UX on the Build menu. Now, instead of having to leave the build menu, select a different colony and click "Build" again, you can just swipe left-and-right to switch between your colonies in a given star. It's a little hard to see from a static screenshot, but I think this should give you an idea:

But after play-testing this for a while, it actually make a pretty huge difference to the speed at which I can bring a new star up to max. Some of the other changes I've made in the latest update should allow for more parallel requests to the server, which further boosts performance. I find now I can queue up builds as quick as I can swipe between the views, and the only thing that really slows me down is waiting for a notification from the server that a build has completed before starting the next upgrade. (The notifications use GCM which I have little control over, unfortunately).

On thing I have noticed is that the client can sometimes get out of sync with the server, especially if you're powering through the upgrade/accelerate cycle. In that case, you might notice that the UI says you're only up to level 3 but when you try to upgrade, you get a "already at max level" error. In this case, you can re-sync the view with the server by exiting out of the solar system view, back to the starfield and going back in again. It's a bit annoying, but I'll be working on these kinds of sync issues over time.

Alliances have been a much-requested feature in the game, and some people have even formed "informal" alliances despite the lack of any actual supporting features for alliances in the game. So I've been working over the last week or so to get some basic functionality in place to make the formation of alliances a bit more "formal". What follows is a basic overview of how I see them working.

Overview screen

The first screen you'll get is the "alliance overview" screen. This'll show you your current alliance and a list of all the other alliances in the game. Here's a quick mockup of what that will look like:

On the left is the "overview" tab. If you currently belong to an alliance, it'll be shown at the top. Underneath is a list of the other alliances in the game. The details you'll see here include things like the number of members and -- in the future -- the alliance's rank and so forth. If you don't belong to an empire currently, you'll have a button at the bottom to create a new alliance. Alliances cost $250,000 to create (they need to expensive because I don't want new players creating them, and I want to make sure you're really serious about it before you start).

The tab on the right is the "Requests" tab. I'll get to how you join an existing alliance in a second, but basically you send a request and existing members vote on whether to accept you or not. I haven't worked out exactly how many votes it takes, etc, though most likely it'll be based on some kind of ranking system within the alliance (i.e. if you have the rank of "General" within the alliance, it'll count more than a rank of "Private", etc).

Alliance Details screen

Tapping on an alliance from the overview screen will bring up one of three other screens, depending on whether you tapped on your own alliance, an enemy alliance or if you don't currently belong to an alliance.

Joining an alliance

If you don't currently belong to an alliance, then tapping on one in the "alliance overview" screen will bring up something like the following:

This shows you a bit more detail about the potential alliance. The list of members is at the bottom, you'll be able to tap on them and see where there are in the map. To join the alliance, you'll tap on "Request" which lets you send a custom message that'll appear in the alliance's "Requests" list that we saw above.

Your own alliance

If you already belong to an alliance, then when you tap on it from the overview screen, you'll see something like the following:

Because it's your own alliance, you can see your current bank balance and you can deposit/withdraw money from it. For the initial release, there probably won't be any requirements on how much/how often you can withdraw, but a history will be kept so that if someone takes too much you'll be able to kick them out or whatever.

Again, you can see all the members of your alliance and tap on them to see them in the starfield view and so on.

Enemy alliances

If you tap on an enemy alliance, you'll see something like this:

As you can see, I haven't decided what'll go in the section marked with a "?" so there'll probably be nothing there for the initial version of alliances at least. But maybe some kind of diplomacy options such as declaring cease-fire, declaring war and so on.

Other features of alliances

Also in the initial release of alliances, I'm planning to add alliance chat, which will be a separate tab of the "chat" window where you can chat with your alliance members privately. There'll also be "flair" for your empire so you can see in the various screens which alliances people belong to. And possibly a few other features which'll make navigating your alliance a little easier.

In future releases, there'll be more features for managing your alliance, such as being able to assign ranks to people, kick people out of your alliance, build teleporters and so on.

There's quite a lot of UI to add here, so it has taken a little longer than I'd hoped to get the initial release out, but hopefully within the week we'll see something.

Up until now, the only source of income for me from War Worlds has been the ads that show on the starfield and solar system view. But my costs have not been zero, and so far hosting is costing me about 10 times as much as I'm getting back from the ads (mind you, we're talking around $2 per day for hosting and 20c per day in income from the ads, so it's not exactly breaking the bank yet...)

However, I've never wanted to do in-app purchases that basically result in pay-to-win, where you get some sort of in-game advantages for paying money, and that's definitely not going to change.

Renaming Stars

So to help me out a little, in the latest update you can now rename stars which you control, for a one-time fee of US $0.99 (or whatever local equivalent). So if you want to rename 5 stars, it's 5 x $0.99 = $4.95. You can rename stars as often as you like, though it's $0.99 each time. You can only rename stars which you have a controlling number of colonies on (so if you share the star with another empire - natives don't count - then you can rename it only if you have more colonies than the other empire).

I'll have some screenshots of the flow once the update has made it through the Play Store (I can't do "real" purchases on my device until it's in the Play Store).

Tactical Map

Also in this update is the initial version of the tactical map. The performance is pretty attrocious at the moment, and it's missing a lot of features (for example, the stars are just represented as red dots, whereas I'd like to see them coloured to indicate what kind of star they are). Here's a quick screenshot showing what it looks like right now:

As you can see, it's definitely quite basic. But you can see there's some empires butting up against each other here, it's getting exciting!

Using the tactical map is quite simple, you just click the "Tactical" button from the starfield view, and it'll zoom out to the tactical view, centred on the same view you had in the starfield view.

Double-tap on a star in the tactical view and you'll zoom in to that star in the starfield view. I've found this is a great way to quickly zoom around the map and see exactly what's going on.

Of course, there are plenty of features that can be added to the tactical map, for example it just colours the areas based on which empire owns the stars. It could also put the name of the empire there. And as I said above, I'd rather like to see the stars coloured such that you can tell if it's yellow, red, blue, black hole etc. That should help you keep your bearing a little better. Finally, perhaps some kind of info panel could pop up when you tap a star.

Bug Fixes

And of course, there are numerous bug fixes and crashes fixed in the latest update. New features like the above always introduce the possibility for new bugs as well, though, so please keep reporting them!

One of the common feature requests I've had for War Worlds is tha ability to "zoom out". I think it's a good idea, to help you plan your empire's expansion and also to help you find where your opponents stars are more easily.

But I think just a simple "zoom" function, which would just render the current view, but smaller, is not that useful. You want something that presents the extra information that you can get from a wider view in a new and useful way.

So to that end, I've been playing around with the idea of a "tactical" map. The idea of the tactical map is that instead of rendering the starfield as it appears in the regular starfield view, you get a view which removes a lot of the visual clutter and just presents the interesting information. In particular, the main point of the tactical map is not so much the individual stars as extent of your (and your enemy's) empire. A picture is worth a thousand words, so here's a quick example of what I'm thinking of:

What you see here is just a test app I made to see what it looks like, but basically the red dots would represent stars and the green shaded areas represent area of influence. Basically, each of the stars inside a green shaded area is colonized by an empire.

So what this means is, if you were the guy on the left in the image below, you'd see quite clearly that the guy on the right is up to something...

This is just a quick test app I threw together to see how it looks, but I think this could be useful. Obviously the shading is not that great (it'd be nicer if the edges were smooth, say) but it's not bad for a first pass, I reckon.

You could tap on the individual stars (points) to see a little bit of an overview of what's going on at that star, and the ability to zoom into the full starfield view and then back to the tactical map would be have to be pretty seemless as well.

Of course, it'll take a little while for this to be integrated into the game, and I'm definitely interested in hearing anybody thoughts on this before I take it much further. Reach out in the comments below (on our Google+ community) with your thoughts!