[Fwd: Re: [MUD-Dev] Metrics for assessing game design]

[ceo]

David Kennerly wrote:

> I apologize for taking so long to reply.  I'm glad you posted it,
> and I think the principles you mentioned are worth considering.

[Me too, now. Better late than never :)]

Thanks. As I said, it's very much a work in progress, but I'm
delighted to now be getting some serious feedback - which is a lot
more than I've ever had before (except from close friends). Provides
me with direction on what needs to be done :).

> Maybe I'm mistaking parlance.  I would expect a metric to contain
> a standard

No you're not, it's my problem :). I'm still experimenting with the
vocabulary I use to talk about this, and with working out what needs
adding to it - I picked up on JC's use of the phrase "objective
metrics", and realised that was probably a better way of describing
what I was doing than what I had been using.

...and I do have scales of measurement, with units on each, but they
are qualitatively defined units, based on observations -
e.g. scale.1 = A AND B AND C, scale.2 = A or B AND C, etc. I'll try
to produce something closer to a real metric :). I've only briefly
touched on them, and now I see it would be worth actually saying
more about them :)... Doh.

>> Worked examples:

>>  Bomberman scores very on question one; every bomb re-shapes the
>>  level (Which DOES matter because it alters how and where you
>>  will meet your enemy). Even movement scores moderately well,
>>  because of the slow speed of movement. Even choosing which
>>  powerup to pick up scores well, because the fuse on bombs is so
>>  slow that you have time to massively alter the effect of your
>>  bomb (by picking up new powerups) before it goes off - and when
>>  you start, the other player could be "trapped, but safe" but 3
>>  you start, the other player could be "trapped, but safe" but 3
>>  you start, the other player could be "trapped, but safe" but 3
>>  you start, the other player could be "trapped, but safe" but 3
>>  seconds later "trapped, and about to die".
>>  seconds later "trapped, and about to die".
>>  seconds later "trapped, and about to die".
>>  seconds later "trapped, and about to die".

>>  The framework/metrics above suggest that bomberman could be
>>  improved by adding "powerdowns". These would increase the
>>  ability to alter the available actions: they give you some
>>  potential opportunity to "conserve" powerdowns in case you
>>  became trapped by a combination of your own bombs and other
>>  people's. You could then downgrade your bombs, enabling you to
>>  stand closer to your bomb without being caught in the explosion,
>>  and possibly even providing safe space for you to survive.

> There's a couple of things I'm unclear on.  Primarily, how does
> the "framework/metrics above suggest that bomberman could be
> improved by adding 'powerdowns'"?  Although I see your supporting
> evidence, I don't see a chain of derivation from the framework
> proposed linking to this example.  There are many things that
> could satisfy the evaluation criteria that you listed.  Why a
> powerdown in particular?

Sorry, again my fault. There is a worked chain here, but I did it
mentally, and just leaped it all in one step when
explaining. Probably partly in an attempt to keep the lenght of the
post down! I try to explain a bit better, but I'm afraid I'm still
not being precise enough (I'm having to work 7 days a week right
now, so I haven't got much time to think about this post - or else
I'll not have time to write it :( ).

I'm afraid that this discussion breaks down (or is about to) largely
because of the variety of implementations. OTOH, it's provided a lot
of useful data to help me see where the theory needs extra detail. I
can use this discussion later as a yardstick to see how effective
the unit-based measurements are coming on :).

As you highlighted, towards the end of the game the available
actions become more and more reduced because of the increasing power
of the bombs. This is a good example of the "guarantee the
game/loop/etc will end" game-design - bombs becoming so powerful
that the rate of deaths increases considerably (although with good
players an explicit time limit is often necessary too) . The third
phase of the game suffers in particular because all the obstructions
have been removed, and with huge bombs the only strategies left to
players are either to duel "mano a mano" or to run around and hope
the other player accidentally kills themself (or gets squashed or
draws if there's a time-limit on the level).

This provides a total of only 3 strategies in the end game, and in
general only one (or sometimes two) of them is particularly
effective (duelling/evading) unless you are very good at
evading. There is a third strategy floating around here for advanced
players - psyching out the opponent. For example, appearing to be
aiming for a draw is a strategy that can be subtly used against your
opponent in psychological terms, especially if you're known to do it
(c.f. articles on sirlin.net I've quote in the past for several
lengthy essays on this kind of strategy in fast-paced/arcade games).

The problem is that for anyone who isn't extremely good there are
really only 1-2 effective strategies at this point. So, there's a
need to keep the available number of strategies up higher at this
point (the game has a very low rating on the "number of available
strategies"). Since many of the implementations always have powerups
on screen (and drop them randomly if there are no obstructions left
to blow up), they could reverse the removal of available
strategies. A powerdown comes from the answer to the question How
can we reverse this removal? Other suggestions might include
attenuating powerups (fade over time) - but rating the resulting
game quickly shows that at first glance that could again reduce the
available strategies because of the tendency to end up without any
powerful bombs.

> The secondary point I'm confused on, which may be related to the
> primary, is the details of the powerdown.  The Bombermans I've
> played have one bomb

...

> five keys on a keyboard.  Only five.  That's beautiful.  So how
> does the powerdown get activated?  Or, is it picked up like a
> powerup is picked up?  It seems like this was not what you
> intended, because almost no player wants to pick up a blast range
> reduction after rushing around the board to grab as many blast
> range increases as possible.

The intention was merely to have them function identically to
powerups, possibly remaining on the board longer, or being
indestructible (at this point the particular details of each
implementation start to make it hard to generalize in such
detail!). An oft-used tactic (with powerups) is to line up several
power-enhancers, set off a load of bombs near to your opponent, so
they know how big your range is, then set off a few more too far
away to hit them, but race along your line of powerups, growing your
range considerably in v.short time, and tripping up your opponent
(especially effective with opponents who play "close to the wind",
relying heavily on knoledge of your power). Similarly, I'd expect to
see people "conserving" powerdowns merely by neither picking them up
nor destroying them.

Many times I see players inadvertently picking up more powerups than
they intended to. I've often seen it as a tactic - force a player to
pick up an extra powerup or die. (Note: It is MUCH MUCH easier to do
this than it is to foce them to "die or die", because powerups just
require you step on a certain square at any moment in a large range
of time, whereas bombs only kill you if you are on a certain set of
squares for a comparitively very short range of time.)

> This blast range is critical for preventing an endgame stalemate
> between timid players.  Otherwise it can often be a stale cat and
> mouse ending.  Of course, there's other ways to solve this, but
> the powerdown as proposed as an isolatable improvement would
> reintroduce the problem that the powerups solve.

IME of playing too many variants for far too many years, always MP,
the "low power" endgame is generally not problematic except:

  1. with novice players

  2. or with variants where players move too slowly

  3. or where players are v.effective at winning/losing/drawing
  before they reach the endgame, so they don't get much practice :)

  4. ...or both players are cowards, and just sit in opposite
  corners ;).

Good duellers are almost as effective right the way down to
only having two (often weak) bombs (I've known people who could win
the vast majority of games with only one minimal-power bomb, but
they were exceptional).

At the same time, IMHO what you're pointing out is the main reason
why many variants have a time-limit per level, and start destroying
/ blocking-off the level (or just declare it a draw if it takes too
long). Comparing the games that are with and without the time limit,
I'd have to say (IMO) those without are better, because they give
the end-game time to ripen and mature :). Of course, other design
criteria are evident here - if you're designing a game that you want
people to play on a console, typically for 15 mins at a time, each
round has to end pretty quickly, guaranteed. I'm not denying time
limits are a good solution for that, just saying that I'm
conveniently ignoring such externalities here.

> Some of the excitement of bomberman is the problems you proposed
> that a powerdown would solve.  It is precisely because one can be
> cornered into no safe place to survive that enables the masters of
> bomberman to make mortals

..c.f. comment above. I've played with people for whom a lack of
powerups was no problem. Despair set in when those of us who played
with individuals like this noticed we couldn't survive even when we
just tried to run away from them :). It's pretty difficult to evade
someone on a non-toroidal playing surface with lots of
obstructions. Generally you were moving too fast not to make a
mistake sooner or later, and the long delay between being able to
change direction (other than backwards, which is usually suicidal if
a bomb-wielding homocidal maniac is on your tail ;) ) if you make a
mistake usually gave them plenty of time to react.

> of us all.  This facet of the game design is enhanced by the
> inability to reduce bomb range.  Because then the firepower up is
> not only a strategic advantage, it is a tactical test of how well
> the player can use the additional blast range.  It kills either
> player equally well.  Heated endgames of bomberman sometimes
> completely consist of masterful bomb placements.  The lack of
> powerdowns rewards this skill mastery--to a good end, too.

The counter-examples I supply are not intended to say "you're
wrong", but instead to show that your statements are a little less
absolute than they come across. and hence your conclusions probably
ought to be prefaced "So, in some situations...".

Adam M
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