Thursday, June 7, 2012

Whale Trail 2.0: Developer Analysis

Note: If you haven't played Whale Trail, go do so, it will make this post far more understandable and it's awesome (and free). iTunes Link.

Ustwo co-founder and wigged evangelist, Mills, has been hyping a reboot of Whale Trail with tweets like, "I can't wait to Free Willy", making it quite obvious that Whale Trail was about to get a freemium makeover.

As an avid Whale Trail fan, and a developer, I awaited with great anticipation for what this AAA developer's take would be on the always evolving "collect & spend".

As evidenced by this very post, it was a gold mine.

First Impression

WOW!  So many things are done right.  Simple and easy (albeit familiar) methods to purchase and spend in-app currency (Krill - awesome).  Most currency will be spent upgrading Willow's main attributes:

  • Frenzy Length
  • Frenzy Blast
  • Cloud Resistance
  • Max Trail Length
  • Max Multiplier

Additionally you can purchase one time use power-ups:

  • The extra life: Respawn
  • The "fast-forward": 8x multiplier
  • Whale Trail specific powerups: Trail Fill & Insta Frenzy

There are a slew of cosmetic upgrades that are irrelevant to the scope of this post, but they are entertaining to say the least.

Pricing of early upgrades is near perfect, and in the beginning, upgrades come after almost every play.  This is essential to getting users hooked.  Failure to achieve this leaves them feeling lost and unmotivated: "Why am I collecting [currency] again?".  

This early euphoria continues...

I truly can't believe I haven't seen more of this: in-app currency reward is bound to the core game metric: points.  More often than not you will see independence, like Limbic's Nuts! or Imangi's Temple Run, where you are trying to accomplish one thing with currency collection being somewhat tangential.  While doing this creates an additional challenge (and an additional upgradeable), I always find it more chore like and frustrating because I'm not being rewarded for surmounting the core challenge.

In Whale Trail, at the end of a game, your points are divided by 500, and that is your krill reward.  500,000 points?  Here is 1000 krill. Love it.  In addition, you get krill bonuses for various achievements or "Missions" as they call them.  Another step in the right direction, but the reward amounts are far too flat, and far too low to be interesting.  You end up accomplishing most of them by accident.  

One mechanic I've been obsessing over recently, and is prevalent in Whale Trail, is the slot machine.  Simultaniously, I've been interested to see how certain games "grease the gears" to get users in the habit of using consumables (See any NimbleBit title, or the new Mega Run).  

Whale Trail nails both with one hammer, well, almost nails both.

On your journey, you'll encounter mystery pick-ups.  You don't get to find out what they are until the end of the game.  They can be a krill bonus (25, 50, 100), or very frequently, one of the consumable power-ups (but never an extra life). 

Nice, an awesome slot machine that dispenses loads of gear grease. Take notes, devs.

However, once again the krill bonus is too flat. Later in the game a +25 krill bonus is like getting a rotten egg. What if one in a hundred was a +1000 krill or even +5000?  Like any good slot machine, the chance of an epic win makes for true addiction.

Euphoria still intact, I continue.

Whale Trail is a difficult game, and it got more difficult with this update.  This by itself is not a problem, in fact, I think it's great!  When I'm playing Whale Trail this time around, games feel more concise, and when they last, it's a rush.  The level design is great and more varied than version 1.

I Hit a Wall

Right around the time you start occasionally getting 500,000 points it seems almost impossible to do much better.  Worse yet, you often will score < 200k points with full upgrades.  You think to yourself, "Man, I got that score with half the upgrades I have now, wtf!".

There are many reasons for this, and I've been thinking all morning how to properly explain them.

Double threat.

The game faces the problem of having two (seemingly) linearly increasing difficulties which combine to create an exponential difficulty.  As you progress, the cloud mazes become more difficult to navigate, and the scattered colored bubbles become more sparse.  These two difficulties also interact.  Having fewer bubbles makes it harder to spot the best path and harder to recover from an increasingly likely collision with a cloud.

Many games have multiple increasing difficulties, but in Whale Trail they form an all too steep exponential difficulty experience.

Don't double punish me bro!

The point multiplier is the heart of progress and replay-ability in many mega hits.  Think Tiny Wings and Temple Run.  Whale Trail's approach is great: You can upgrade you maximum multiplier, but you have to re-earn your multiplier each game.  

Higher multipliers are reached sequentially, so it takes a long time in each game (even with the 8x head start) to collect enough colored bubbles to get the multiplier to your allowable max.

The extreme challenge comes with the fact that getting zapped by clouds not only drains your flight fuel, it also drains your multiplier!

So even if you manage to get that 32x multiplier, then hit a patch of clouds and manage to survive, you're left with a 4x or 8x multiplier. What is the point in continuing?  There is no way with sparse bubbles and crazy cloud mazes you are going to be able to regain the previous glory that was only possible with accumulated success from the easier beginning. At this point dying actually becomes desirable when Krill farming.


Here is how I visualize the difficulty variables previously mentioned:

I then multiplied these variables and some logical weight values and graphed the result - a very crude way of approximating overall difficulty.

I also graphed two examples for aggregate Krill collected in a run: one when making few/no mistakes, and one when making an early, harsh, but survivable one (Maybe you use a Trail Fill power-up to recover).

I want to see krill collection correlate somewhat closely with difficulty, but it doesn't:

Things that are wrong to me:
  1. Difficulty seems Exponential.  Obviously my numbers are made up here, but i'm just trying to quantify/visualize my experience.
  2. A mistake will end you.  If the mistake doesn't take your life, it will lead you to the next issue...
  3. No way to recover Krill/Point collection. As is reflected in my graph, with the low amount of bubbles in the late game, it is just not possible to get your multiplier back up when it takes a hit.
  4. End of your life sucks.  Except in the case of sudden death, your last moments in Whale Trail feel like a pointless struggle as you aren't earning many points/krill. Instead, these moments should be the most profitable.
  5. Trail is too elastic. It grows and shrinks too quickly

  • Adjust difficulty so that the late game is very slightly more survivable/recoverable. Addresses problems 1, 2
    • Show the paths of moving clouds
    • Increase the number of bubbles in the late game - no need to make consistently more, but add occasional dense pockets/strings. (also see trail suggestions to see how this won't be a big deal).
    • Don't make the camera zoom in so much when you are down low
  • Remove the multiplier cloud penalty Addresses problems 2, 3, 4
    • It's hard enough to get the multiplier maxed, no need to take it away
    • To manage high scores take control over length of play
  • Make the trail less 'elastic' Addresses problems 1, 5
    • Increase the max trail 'length' (not visually)
    • Make each bubble grow the trail less
    • Don't change how the multiplier grows
  • Use a more complex/fair cloud zapping scheme than ~2 zaps per second - goal: avoid punishing small mistakes. Addresses problem 2
    • Reduce cloud collision area by 10%-20% (perhaps make a function of cloud resistance)
    • Modulate collision damage by direction of travel relative to cloud.  1 - (Dot product of direction of travel and vector to center of cloud) = forgiveness factor when grazing
    • enter cloud from sky: zap
    • enter cloud from another cloud: no zap
    • zap 1 per 1-1.5 seconds after first zap while still in cloud
    • If finger is pressed (you are changing direction) zap twice per second
  • Ask for a review after the player's first 200k/300k/500k point run - there is no reason this game should have anything less than 4 stars.
  • Increase Upgrade Pricing. Many of these changes will naturally lead to more krill earnings.  No need to try to scale down scores.  Just increase higher end upgrade pricing.
    • Throwing a number out there, but just raise current prices to the power of 1.2 (eg 10 -> 16)
    • Consider making the top multiplier upgrade even more elastic say raise to the power of 1.3
  • Minor Suggestions
    • Make mission rewards larger
    • Make wildcard reward krill bonuses more elastic

I hope this analysis gives other devs some insight as to how I look at certain game attributes. In general, I'd love to see more devs sharing their technical perspective on mechanics.

I love Whale Trail, but more importantly, I love how Ustwo strives for excellence and embraces change.  

UPDATE: 7/2/2012
Whale trail was update with a few changes to ease difficulty and promote fun. The late game is more survivable/recoverable (both in terms of trail and multiplier) and there is a temporary +500 krill slot machine reward - all steps in the right direction - but missing the key element of making the late game the most profitable by removing the cloud multiplier penalty.


  1. Nice review. Are you going to do reviews on other games?

    -Paul Solt

  2. there is a rare 500 krill bonus for the slot machine