Case Study: Risk/Reward in Imperishable Night

Character Select

Your first big risk/reward choice.

I’m trying to avoid having Touhou games take up too much space here.  I don’t want to turn into “another guy on the internet who won’t shut up about ZUN’s Shmups.”  But deconstructing them lately has been fairly fascinating stuff, and I wanted to take a moment to talk a bit about what seems like a high point in the series – Touhou 8: Imperishable Night.  It has a lot of neat things going for it, but I’m going to focus on one particular aspect of its design:  Layered risk/reward mechanisms.

Imperishable night has a surprising number of places where you have to make choices while playing – tradeoffs between risk and reward.  They tend to have varying game effects, ranging from higher scores to harder patterns.  The most basic is at the beginning, when you pick a character.  One character is far more survivable.  Another has better score potential.  Others have different tradeoffs.  After the game starts though, it gets a lot more interesting.


POC zone

Hideously unsafe, but look at those points!

The most obvious tradeoff is probably in point collection.   Point items in Touhou tend to have a base worth that is set by some other value.  (In Imperishable Night, it’s the number of Time Orbs you have collected.)  But they are also affected by where they are collected.  Point items collected near the top of the screen are worth their full value, but as they get closer to the bottom, their value drops off rapidly.

And naturally, the top of the screen is generally a lot more hazardous, since enemies tend to approach and attack from the top.  So choosing to go for more points almost always puts you in harm’s way.

Just to sweeten the pot further though, there is also something called the “Point of Collection”, usually abreviated POC.  It is a sort of autocollect zone.  If the player moves high enough up on the screen, they reach a point (usually around 75-80% of the way up) where all items on the screen suddenly home in on them and are collected automatically.  In addition to making it much easier to collect widely scattered items, any point items collected in this zone are worth their maximum value.  So not only are players encouraged to collect items higher up, but the POC means that even if they missed an item and let it fall, they can still get it at max value…  As long as they’re willing to make a foray into a highly dangerous area.



Of course, sometimes it's hard to avoid grazing even if you want to...

I know this one isn’t unique to Touhou, but since it’s right there in Imperishable Night, (and is basically a textbook example of a risk/reward tradeoff) it gets its own section: Grazing.

It’s a pretty direct encouragement of  risky player behavior:  The game flat out rewards you for flirting with death.  Flying close to bullets without getting hit yields powerups called “time orbs” which directly contribute to score.  So this one is pretty blatant:  Want more points?  Live on the edge!  Even when not trying for a high score, it’s often worth engaging in this sort of behavior, since more points still mean more 1-ups.  (And collecting enough time orbs per level effectively gives you extra continues as well.)


Master Spark

Final Spark: It's like Master Spark, but it costs two bombs. And it's more final.

And then there’s bombs.  That staple of SHMUPS, which I already spent too much time gushing over in an earlier post.

Bombs have some interesting properties in Imperishable Night.  On one hand, they still fill the same general function they do in most shmup games:  They hurt everything on the screen rather significantly, and make you invincible for a little while.  They are the ultimate “ack I don’t want to die” card.

They usually do around 40-60% of a boss’s lifebar in damage.  So while they don’t allow you to completely skip a boss form, they still let you skip most of it.  And since they usually clear all the bullets from the screen, they at least make bosses significantly easier.  Using a bomb on a boss does mean you won’t get the score bonus, but that’s usually secondary to survival.

The fun part though comes from what the game calls “Last Word” attacks.  When you get hit, you have a very short window of time where you can fire a bomb to save yourself.  It’s not very long, but it is [barely] possible to do on reaction in response to getting hit.  And if you trigger a bomb this way, it does about 50% extra damage, killing or gravely injuring most boss forms in one shot!  Except… it costs you two of your bomb stock instead of one.

So even if you’re not going for score and are just going for survival, you have an interesting choice here.  Bombs are almost like one-ups.  You can spend one to keep playing when you would otherwise die.  So imagine:  You have just reached a boss that you know is hard.  Do you use a bomb early, even though you’re not yet about to die, to guarantee it costs you exactly one bomb to make it through?  Or do you try to tough it out, trying to save your bomb for later, but knowing that if you do screw up and get hit, it will cost you two bombs?  Choices, choices…


Moon Princess, hiding behind familiars.

The moon princess, hiding behind a wall of familiars.

Finally, there is an interesting risk/reward mechanic inherent in the enemies themselves, in every single game level:  Powerful enemies will spawn “familiars”.  Familiars are basically little linked sub-enemies.  They frequently follow their master around, and often shoot at you, or are part of bullet patterns.  They can be destroyed individually, or you can just blow up their Master, and they will all explode as well.  Destroying familiars doesn’t directly kill the master, but he does take half the damage you inflict on his little friends, so it is still useful.

Familiars are often annoying.  Destroying them can significantly reduce the number of bullets being shot at you in a pattern.  But it also means that you have to endure the pattern for longer, because you’re blowing up the little buggers and not their boss.

Familiar clearing bullets

Destroying familiars can sometimes remove a lot of bullets.

So already there’s an interesting choice to be made.  Destroy the guns, or go straight for the core?  The game makes it easy to act on this choice – when focused, (using your more powerful, narrow shot) you can’t shoot (or collide with!) familiars, so even if the boss is hiding behind them, you can aim straight at them.  If you’re unfocused, then you attack familiars as normal.

It gets better though.  If you blow up an enemy and cause their familiars to explode as a result, those familiars will clear bullets in a small area around themselves.  Since those familiars are often the source of those very bullets, in some cases this can be a tremendous help, if you think you can destroy the master quickly enough.


So I’ve listed here a bunch of interesting mechanisms whereby the player gets to choose how risky they feel like being.  All of these are interesting examples of risk vs. reward in a game.  But what makes them particularly interesting to me isn’t just that they are choices.  Most games have choices.  What makes these interesting is that they are all present and happening at the same time. They are all choices that the player can make at any time while they’re playing, and which overlap in some interesting ways.  But even more than this, they are choices that can be skipped, as well.  You can easily play the game without knowing how point scoring works, or about the exact mechanics of familiars.  This is frequently called depth in a game, and is generally the mark of a good one.

As Sid Meier once observed, games are a series of interesting choices.  I am beginning to think though, that good that a series of choices may be, choices in parallel are better.  No other Touhou game has had as many of these mechanics layered together as Imperishable Night.  (Most have some subset of the list above.)  And (in my humble estimation at least) no other Touhou game has better basic gameplay either.  I’m suspecting it is not entirely coincidence.

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