Wednesday, October 12, 2011

Steambirds: Survival Mobile

Today, we are launching Steambirds Survival for iOS. The layout has been rejiggered to work nicely on the iPhone. And there's a wonderfully expansive HD version for the iPad that it easily my favorite way to play Steambirds. The Android version will follow shortly.  All of them are free, so give it a go and let me know what you think.

Though this new mobile version of Steambirds Survival shares the same name as web-based game, by partnering with Halfbrick (of Fruit Ninja fame) we've transformed it into a much bigger (and my opinion, better) game.
  • Improved progression system with new missions:  There are 64 missions, 8 of which are infinite survival modes.  If you liked Steambirds and want to play it forever, this is your game.  (Sometimes you need something a bit meatier than a tiny handful of puzzle levels.)
  • Free-to-play:  This is our first free-to-play game on mobile.  Like most of our games, we take the 'free' part pretty seriously.  I want people to buy because they love the game and can't get enough.  I'm very curious what lessons we'll learn. 
  • Multiple player planes: We added a really fun recruitment system that lets you hire multiple player controlled planes.   Running through a level with three Chickadees feels amazing.  Previously lackluster planes like the Cockroach turn into fascinating exercises in multi-plane tactics. 
  • New Reinforcement powerup: You can call in NPC allies to fight along side.   This leads to rather epic mix ups with dozens of planes pinwheeling about in a deadly dance. 

Does your game have a clear "Arrow of Play"?

After launching the web version of Steambirds Survival, I was unhappy with the mission structure.  Originally there was an open list of planes that you could unlock in any order.  It seemed like a good idea at the time since 'openness' and 'choice' are good, right?  But we saw that a lot of players would cherry pick a few planes and then after they found one that they liked, they'd just play that plane to grind the in-game currency, copper. As a result, the progression lacked a clear feeling of momentum that encouraged you to trying out a wide variety of different play styles.

With the new mission structure, you unlock cities one at a time and each city reveals more cities to play.  Within each city, there are 8 sub-missions that give the player to demonstrate increasing levels of mastery to pass. Now, there's a very clear direction to the unlocking and this should give players short term and long term goals to work towards.

In physics, Arthur Eddington coined the phrase 'arrow of time' to describe how time appears to flow in a single direction.  As you dabble in general relativity, you realize that time is wonderfully compressible and can be manipulated in a variety of clever ways, especially near the speed of light.  Yet even with all this variation, it consistently advances forward.

When I look at a design, I always ask "What is the arrow of play?"  This is a directional property of the mechanical systems that always moves the player forward. And like time, there's often a surprisingly amount of variation that occurs along the way.  Some players advance slowly, others take strange side paths, but all advance.

Tools for creating the arrow of play

In Steambirds Survival, there are a variety of systems that result in a distinct arrow of play.
  • Inevitable decay: Plane health almost always goes downward.  There are very rare health boosts, but they are at best a temporary reprieve. 
  • Escalation: Enemies slowly increase over time.  Waves get larger.  Difficult enemies spawn with increased frequency.  Even the best players find themselves at a point where they can't fight back the chaos any longer and errors creep in. 
  • Short term goals: Short term, you are trying to live long enough to complete mission goals that are just on the edge of your capabilities. 
  • Repeated patterns: Each mission goal unlocks new mission goals.  Once you learn the pattern you can repeat it again and again building momentum like train wheels accelerating down the track. 
  • Resource flow: Each goal you complete earns you copper, which you spend to either facilitate the completion of goals or to unlock new cities. There is a clear resource flow from sources of currency to sinks of currency. 
  • Limited choices:  Unlocking new cities in turn lets you unlock more cities, eventually getting to the point where you have explored all the content in the game.  At once point in my career I thought linearity was a curse. And it is when taken to extremes.  But it is also a tool.   If you end up overwhelming most players with too many choices, the perceived quality of the choices provides goes down.  In Steambirds Survival, there are always at least 4 choices.  You can unlock up two cities.  Or you can attempt missions in at least two cities.  The hope is that it is clear what to do next. 
  • Linear affordances:  The map of cities is a simple list that scrolls in along one dimension.  Should I have made a map that scrolls in two dimensions?  I could have, but I'm not sure it would have improved the quality of the choices that the player made.  Instead, by restricting the dimensionality of the UI, the player can focus on picking a city instead of wandering around a map, trying to remember which corner the next locked item is located at.   (I learned this lesson from map scrolling in Lemmings.  One of my favorite tools for simplify interfaces)
Games are about change.  The system moves from one state to another at the poking and prodding of the players. Each tick of the clock or press of a button creates momentum that leads the player on a joyful rush through challenge after mastery challenge. You start slowly.  The player builds speed and eventually they steam forward in a continuous state of flow.  The arrow of play leads inevitably to a sense of pacing.  Yet critically it approaches these not from a traditional narrative perspective, but as a property of the game systems.  The beats of the game rhythm are those clicks and taps turning tight loops over and over.  Steambirds is a turn-based strategy game, a genre typically seen as a slow and plodding.  Yet in the middle of a dog fight, it can feel like an action game.

A system that lacks a clear arrow of play results in players being mired in odd dead ends.  It isn't enough to make a game that has feedback loops, widgets to master and all the various atomic elements of a game.  It also needs a strong sense of momentum that like time or entropy hurtles the play forward.

take care,


  1. Yay! Android version! That might mean that Triple Town is coming to Android too! (Steambirds looks great and I will definitely download it, but Triple Town is... argh... *so* addicting).

    Anyhow... congratulations, and best of luck!

  2. My main commentary on the steambirds survival game is the absolutely atrocious placement and integration — or rather lack thereof — of advertisements. They're just blankly overlaid on the menus, it seems, with no frame, nothing to give them a place or make it look like it wasn't some amateur last second decision, and it really looks atrocious. The game itself is everything we know and love, but the advertisements (both the square ones after combat and the banners at the bottom) are really poorly integrated into the game.

    Even a simple frame or something would be significantly better than how it looks now; it's simply jarring and feels like bad UI/UX.

  3. Dan, I'm not sure if you've mentioned it in the blog, but seeing how much you've talked about plagiarism etc in your blog lately (the whole LOLapps and Triple Town hassle - I love Triple Town btw), I just wanted to ask how much the card/boardgame Wings of War helped you along in creating Steambirds?

    I was a bit surprised when Steambirds came out and you talked about it first in your blog, but didn't have any nods towards Wings of War (which was coming to XBLA at one point, not sure if it's anymore). Is it a pure creative coincidence that the design is pretty much 1:1 with the card game (ie. you've never even heard of or seen Wings of War) or is there some other reason you don't want to mention it?

  4. Reko, top-down shooters like this one have existed since forever, as has the notion of momentum being expressed as a limitation on turn rate leading to "faster unit makes larger circles". So this is like Wings Of War only in the sense that two things made from the same set of Lego bricks will look similar.