Sunday, April 11, 2010

Design Post-Mortem: Three Mistakes

While I'm pretty happy with Replica Island, releasing it has definitely been a learning experience.  Some of the design choices Genki and I made were good, others were ok, and a few were bad.  Today I'm going to talk about three mistakes I made in the design of this game.

Mistake #1: This particular jump.

Turns out that a lot of players die right here.  Heck, I have the metrics to prove it.  This is sort of a difficult jump because you have to make it across a wide pit and then land in a very small space near the top of the screen.  This jump started out a little easier, but it got harder when I compressed the vertical size of this level to deal with some camera problems.  The real problem here, though, is the distance.  It turns out that this is the first spot in the game where you are required to use second-order flying skills to reach the other side.

Just what is that skill?  Well, it turns out that some players never realize that they can stay aloft for longer if they let momentum rather than fuel carry them forward.  If you press the jump button and get your speed up in the air, you can release the jump button and stay aloft until gravity overtakes you and you begin to fall.  At that point you can hit the jump button again to combat gravity and maintain your altitude.  You can't do this forever because you'll eventually run out of fuel, but using this method you can jump much greater distances than if you just hold the jump button down constantly.
The real problem is that I never teach players how to fly that way explicitly.  There is lots of tutorial levels designed to make sure you can fly, but it turns out that only the most basic flying skills are required to get passed those sections.  This area is the first in which you cannot progress unless you've figured out how to use the more complex flight mechanics, and people get stuck here.

What can I do about it?  Probably this area itself is fine; a better tutorial on this particular skill is probably in order.

Mistake #2: The Case of the Robot Spewing Spawner

When I made the robot spawners, I though it would be a funny easter egg if you could possess them.  Part of the plan was to allow the possession orb to possess any machine, and I thought possessing the spawners would be a little hidden reward for users that experiment.  The problem is, I added this functionality before we understood how the robot puzzles were going to work; in the final game, it's trivially easy to possess a spawner, and most users are confused rather than elated.  Even worse, being able to possess a spawner sometimes gets in the way of possessing a robot, which is pretty annoying.  I realized that this might be a problem before we released the game, but I left it alone because I thought it was funny.  Now there are multiple videos about it.  Pretty undeniable proof that I messed this up.

What should I do about it?  I should probably turn the easter egg off or at least find a way to make it much harder to find.

Mistake #3: The impossible puzzle.

You have no idea how many people have e-mailed me about this puzzle.  It's clearly the most difficult part of the game for a huge number of users.

In the first version of the game, this section was missing the red spikes due to a bug in the level data, which made this puzzle even more confusing.  But even after fixing that, I continue to get several e-mails a day asking about this part.

If you don't want this puzzle spoiled for you, stop reading now.

OK, I warned you.  The solution here is to use the Possession Orb to grab the robot and run him into the button.  Pretty simple, I thought; the real challenge in this puzzle's original form was actually just maneuvering the Orb through the spikes before it dissipates (in an update I added a gem to this level, so the Orb survives for longer).  But it turns out that users weren't even figuring out that they could use the Possession Orb here, even though they've seen this pattern several times in slightly different contexts earlier in the game.

I finally realized what the real failure is here: players don't realize that the Orb can fly.  The tutorial says something like, "tilt the phone to control the orb," but if you never try tilting it up, you'll never learn that the Orb can fly.  I think that players also forget that the Orb is in their arsenal, but they'd probably figure that out eventually.  Not expecting it to be able to fly means that many don't even try it.  This is a fundamental teaching failure on my part and makes this puzzle a whole lot harder than it was intended to be.

What can I do about it?  Well, as a first step, the tutorial level should force you to send the ball up at some point.  After that though, the game needs to reenforce the fact that the Orb can fly, so I'll probably need to modify some levels to encourage that behavior.

The great thing about this is, I can fix the problems and send out an update and see if my fixes were successful.  And if not I'll try again.  Traditional video games have never had this sort of ability to iterate interactively with the audience, and I'm really learning a lot from it.


  1. I checkout the last Replica Island from svn.
    And test it on my nexus one. It goes well, however, I found the frame rate is just 30~40fps. Why? Slower than G1?

  2. I've mentioned this a few times here before, but the N1 and Droid are both fill limited. With 2.5x the pixel count, it takes a lot longer to composite the frame. Pretty much everything runs at 30 GPS on those devices. You can see that actual game speed is very high, though--at least 10x the speed of the G1. It's just that the big screen devices pay for all those pixels.

  3. Chris, the Robot Spewing Spawner thing is hilarious! The cool thing about it is that inside the world of Replica Island, it makes sense: your possession orb can possess robotic machines, and the Robot Spawner is a machine that spawns robots, so you can possess it to spawn more robots!

    Usually bugs don't tend to "make sense" in that way. Hopefully, you can utilize it and incorporate it into the game in some fashion. Perhaps a puzzle could be solved by being able to spawn a robot?

  4. I thought the Robot Spewing Spawner was pretty fun at first(Thought i found a glitch). But got very annoying. Especially when trying to overtake a robot and accidentally overtaking the Robot Spawner -> which resulted death.

    "v1 missing the red spikes"
    tried that part like 10 times, was trying to somehow fly between those invisible walls of death(missing spikes)...never made it though. also the orb just didn't seem to last long enough. Finally i checked if an update was available and that resolved the problem.

    i think i've got pretty bad framerate issues(using a droid). at time the robot moves super fast to the edge of the screen @_@

    the controls also seem pretty weird at times (maybe just a user problem?) suddenly the jets start going and don't stop until i hit the jump(fly) button. or random movement without me touching the controls o_O

    definitely a great game, was waiting for a game like this for ever to finally use the dpad.

    hoping for a see a new game from the replica team people

  5. Eventually I managed to complete this game, despite the three problems. I do agree the long jump was a bit hard.

    This game is very cute, I really like the android. xD

  6. LMAO, really? I thought that was one of the most straightforward things ever. I had more trouble on getting to my creator at end game with all those spikes and little robots flying at me than I ever had with that little thing. xD

  7. Just wanted to add one little note that you might want to update...

    As I'm looking to upgrade my antiquated G1 with a better phone, I'm looking at the HTC EVO in my future.

    Problem is, there is no keyboard or trackball of any sort. While multitouch support won't help with 1.6 based devices, it might not be bad to consider a multitouch based control scheme (rather than tilt) for the phones that have no other method of input.

    (And it would be EXTREMELY useful to see how you implement!) I fear that given the issues with touch input causing slowdown that it might take some creativity to support a full-time on-screen joystick.. but I'm still a little confused as to how sleeping the touch input works, so I'm talking completely out of my backside.

  8. GREAT game! loved everything. only thing is when i finished the game it just started over. is it possible to go back and play previous levels when you finish? in order to play back certain parts one has to play through the whole game again?

  9. Like what the comment above said. I really want to see all possible endings, but playing through the entire game again is...well, it's a chore.

  10. Well that explains it --> when I first tried to get past here I didn't have the red spikes nor the gem to extend orb time.
    After trying to fly through a couple of times just took it on assumption that you couldn't. Then tried the orbs which wouldn't last - very nearly got the robot but just a milisecond not long enough.

    I even managed to get the robot to open the gate, but meant having to fly midway - and not being able to see the spikes I was trying very hard not to let the robot drop.

    Nice to hear its fixed, might go and try it again.

  11. About "The Case of the Robot Spewing Spawner": I got stuck here too. I went down, got safely behind the spawner, launched my Orb, and then it started spewing when I pressed Jump.

    I was this convinced I was stuck because of a bug, I actually turned off my phone to try the level again. I even believe I got stuck a second time.

    The reason why I believed this to be a bug, is because of how it spawns. It spawns an unrealistic amount of robots, who were going through the walls and all.

    Perhaps you could change the behaviour to spawn one at a time, and perhaps launch them with great speed, so they explode when they hit the ceiling or floor. This way is is more clear that you are actually controlling the spawner, and pro players could even use the spewer to shoot down birds, which sounds really awesome to me :)

  12. Spawner seems to have some type of magnetic pull. I can't get the orb to the bot. It keeps sucking the orb in and won't let me control the bot. Love the game though. Droid Eris.

  13. I don't think you should add anything to the tutorials. One of the things I liked best about this game is that it DID NOT spell things out. Did super mario brothers explain anything? Nope, and solving the puzzles is that much more rewarding because of it.

  14. @Russell,

    Before I shipped this game I would have agreed, but now I think that user expectations are very different than they used to be. Many users see exploration and discovery as design failures. I think those users are wrong, but there are so many of then that I can't discount their opinion entirely.

  15. I didn't figure out the multi-flying thing til later... I managed to get there somehow by using the jump if the pink monster to propell me... Got a much bigger sense of achievement through the trying. I must say I was far more irritated by the level with lots of lava and tiny platforms... Had to complete the while level over and over again. Got really annoyed at my trackball then got stuck in the sky when I finally made it and had to restart the level... But after that I got it on the next attempt... Great game overall though... Excellent stuff... Jacob n1

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  17. The third point above is where I got stuck but not because I didn't realize what needed to happen, its because by the time I got the orb through the spikes I couldn't get it to the bot. It just kept heading for the spawner!

  18. @Chris,
    I have to agree with Russel. After playing this game up to the long distance jump I was bored from lack of a challenge. Once I died I played with renewed vigor :)

  19. Chris, I really enjoyed Replica Island and I really hope you keep on whipping up Android games. I didn't have any issues with 2 of the 3 "mistakes" here, but I did find this blog and this entry because I was totally stuck on your snafu #1.

    Speaking for myself, what was confusing here was the appearance of the whale-thing for the very first time (at least in my order of level play), placed right where the jump needed to begin. I was 100% convinced the whale had something to do with getting me across, and that I was just missing a vital whale-related technique.

    If I hadn't been so focused on the whale, I probably would have used a "burst jump" as you describe; I'd already used them in game by then, just not to that extent, and I didn't think that technique could possibly get me across, thus the "whale puzzle." But it turns out the whale was really... a red herring!

    As for users not wanting to explore, or considering challenges a design flaw, I think this is usually untrue when it comes to classic-style platform games. Early on, I kept looking for more secret stuff in RI's levels, a la SMB1. I think most gamers really like finding stuff like that in games like this. You have to ignore all the idiots in the Market who give one-star ratings to any app that won't make them breakfast in the morning.

  20. Hey, I'm with Russell up to the point of not adding anything, by all means keep experimenting.

    I - not being the average user, but then nobody is - am more interested in exploring the scenery than getting my hands on the gems, stumping and possessing everything on the way or die trying.

    So far I was sparse on my comments but now I really feel like speaking up, because it seems to me that your view is getting biased.

    You have a point here regarding user expectations shift, certainly owners of a game console have different values from owners of a general purpose communication device who are generally more social and would often prefer to chirp than work out a puzzle.
    But please note that those of us that do like the puzzles don't chirp so much, hence the bias.
    That's not to say you should completely ignore the opposition just apply some factoring to it.
    RI doesn't get those 4.5 stars out of million+ ratings for nothing and you devised an enlightening metrics feedback system, use the source Chris.

    Now more specifically to the issues here:

    #1 Flight challenges are great fun- don't lower the bar, but sure give some flight crash-course. May I suggest an high jump to demonstrate the intermittent use of the thrusters, on failure a fall to a pit with the professor giving a lecture may serve as penalty.

    #2 I found it a fun easter egg but guess it ain't much fun getting bugged about it. I'm with Adam all the way here and beyond. To be consistent about it perhaps the doors could be viewed as machines, I will try possessing the turrets as you mentioned somewhere but what I'd really like is to grab Mr. Rokudou by the flying chair and give him a good shake, perhaps even send him to meet the professor face to face and... OK, got a little carried away, excuse me.

    #3 The missing spikes was the only real bug in my view but I never got to experience that as I installed v1.3 to begin with. As it is now the added gem serves as an hint as well as to give more time to maneuver the orb. If you find some other way to drive home the idea of using the orb here, perhaps it would be better to revert this it's really just a short distance.
    Now, this is getting really long so I'd go back to the appropriate post for more on PObs, hope you beard with me.

    All in all FUNTASTIC work, thanks.
    R. Deckard.

    P.S. Brilliant artwork Genki, really shines out the G1 screen.

  21. Let me tell you something about the possession orb that I think is part of the problem here.

    I don't know about you, but I don't hold my phone parallel to the ground when I'm playing the game. I hold it like I would any portable game system-- closer to perpendicular. That made it look like the orb was affected by gravity, because the game would register a downward "tilt" due to the way I naturally held the phone. I spent like half the game thinking that the orb was actually falling to the ground, rather than awkwardly bumping against it.

    Thankfully, though, I figured it out before I got to that particular puzzle.

    Anyways, the best thing would be to word the instructions with things like that in mind.

  22. Memory 37 is just about impossible for me. I can't land precisely enough on the towers and keep dying on the red spikes. I'm not sure if it's my input device (incredible optical pad) or just user error.

  23. Oh. I got really stuck on the long jump for a long time until i read your mistake #1. First my optical trackball is too sensitive(i'm using HTC desire). But the update does improve it. Secondly I died because I keep holding the flight button.You should include some tips on flying in the tutorial. I almost deleted this game due to frustration at that level. Yap, this is so far the best andriod game I have ever played. The only one that holds my interest for a looong looong time.

  24. Hello,

    I'm stuck on your "Mistake #3: The impossible puzzle.".

    I don't know why, but I never figured how to "tilt" my phone to made the possession orb to move/fly.

    I try to shake it, tu turn it on the right, on the left, to hit it, ... nothing made this possession ball move or fly.

    By the way I've a Nexus S if it can help ;)

    Or maybe I'm just stupid not understanding what "tilting" mean (I'm french ^^).

  25. I had to tilt my phone so drastically to get the orb to fly that I could no longer see the screen. I though that perhaps the orb could fly when I reached the "impossible puzzle", but found myself doubting that once I attempted it. I never thought that I would have to tilt the phone a full 90 degrees to produce the desired effect. That being said, I enjoyed the game and it was a lot of fun till that point (and after that point).

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