[MUD-Dev] Player Manipulation of Environment

Jasper McChesney jasperm at student.umass.edu
Thu Nov 29 23:04:32 CET 2001

Paul Schwanz wrote:

[Snip bits on extincion, etc.]

> When it comes to responding to extremes in animal populations,
> however, I don't think we are limited to simply increasing spawn
> rates.  While I haven't fully fleshed out the idea, I lean toward
> having various "genes" that automatically respond to player
> actions in a way that functions something like a crude sort of
> natural selection.  This is off-the-cuff, but I'll give a simple
> example.

I'm a great fan of ALife, and think such models would be really
interesting if implemented in an online world.  I have to question
though, whether it's really a very useful thing to do.  At the most
basic level, you'd be devoting a fair amount of CPU cycles to
determining a lot of things that would be entirely in the background
and probably never surface to player view.  Natural (or unnatural)
selection allows an organism to adapt to its environment -- i.e.
survive better.  Unless your MUD really needs rabits to survive
better, I think it's a lot of work for not much reward.  I guess you
may indeed want better rabbits just to keep the population alive but
to what end?  You'll have a lot of imbalances if monsters start
getting tougher and tougher as the game goes on.  You always (and
I'm speaking with the general "you" here) have to be aware that
allowing a large subsystem of your game to "evolve" freely could
potentially change the game environment a lot. (If it can't, what's
the point?)

> Suppose the wild rabbit has three "genes."

Nitpick: You really mean "trait" (or one of several more technical

>   (h) Higher hit point gene
>   (b) Faster birth-rate gene
>   (c) Better camouflage gene
> Each rabbit has one of these genes that is dominant.  Provided a
> rabbit recieves the proper nourishment, it will give "birth" after
> a certain amount of time.  (This can be a simple spawn nearby,
> since our desire for more interaction with our virtual world
> doesn't necessarily require that we have rabbit sexes or preclude
> the idea of having things spawn into our world.)  When it gives
> birth, there is the greatest chance that the offspring will carry
> the same dominant gene, but a smaller chance that another gene
> will become dominant.  There is also a chance that the dominant
> gene will become more pronounced.  We could test and tweak the
> numbers, but let's assume a 60/20/20 per cent chance respectively.

Just to get off on a technical tanget here, aside from the general
(and very interesting) idea of ALife on MUDs....

Although I'm sure you know that your setup here doesn't strictly
follow the way real genes work, you have two problems, I think.
First, IMO, the whole point of ALife is to run a simulation that
eventually (or continually) comes up with a result -- in this case,
What rabbit-type lives best?  Further, the point of ALife is really
to do this for situations which are so complex that a person can't
just look at it and see how things will turn out.

With this setup, I can look at any rabbits with the same "dominant
gene" and myself determine which is better -- no simulation
required.  Having "more pronounced" versiouns of each dominant gene
seems pointless to me, or at least less interesting than other
options, since the lesser forms are always worse.  It's liek being
given the choice between the shotgun and the super-shotgun in Quake
on the later levels -- why even choose the former (I know, there are
reasons -- not the best example).

Secondly, and more problematic, is the fact that your traits are
numeric in nature and not binary switches.  If I ran it now, I'd
soon enough have rabbits that became better and better: their trait
rating would continue to rise unchecked.  Eventually, you'd have
100% invivisble rabbits -- or whatever other ceiling you establish.
The problem is that there's no disadvantage to becoming specialized
here: no complex interaction between genes.

At a minimum, you don't simply want a "dominant gene" but rather a
total balance between traits.  If a rabbit gets better at stealth,
its other abilities should suffer.

[Snip example.]
> What would this mean?  As I think through the different scenarios,
> a few thoughts come to my mind.
> When a particular area of rabbits came under heavy hunting, it
> seems to me that those with the b-gene would be the first to go
> according to Raph's information.  But certainly those with the
> h-gene wouldn't be far behind.  This will naturally select for
> those with the c-gene to survive, especially those with higher
> levels of the c-gene, since a rabbit with the c9-gene could be
> effectively invisible.  Eventually, hunters will not find very
> many rabbits in that area and move on to other hunting grounds.

I don't quite understand how this is a good thing.  If the purpose
of rabbits (or whatever other player-accessible resource exists)
becomes unaccessible, what's its purpose?

> Since there is a chance that even those rabbits with a high level
> c-gene will give birth to a rabbit with a different gene, when a
> particular area is not hunted heavily, the area will be
> repopulated with rabbits having the other genes dominant.  Soon,
> there may be lots of rabbits with all sorts of genes in that area
> again.

True, if no further "evolutionary pressure" is put on the
population, it would drift back to neutral.  However, my guess is
that players aren't going to entirely abandon a zone like this, and
that some degree of pressure will stay.  Once rabbits develop the
100% invisibility, a rabbit that is visible will just get butchered
and never pass on its genes.  The problem I see is that you're going
to get stagnant populations very shortly that will have no reason to
change in one direction or another.  They're certainly not natrually
going to become less specialized.

> If the area has no other natural rabbit predators, the rabbits
> with higher birth rates will tend to be most prevalent in an
> unhunted area.  On the other hand, if predators are predisposed to
> eat rabbits with lower hit points, then rabbits with the h-gene
> may predominate.

This is the most intersting part of your (specific) scheme: seeing
what rabbit-type becomes dominant in a given area.  I still don't
know what game purpose this really serves though.

> Or consider the case where someone decides to have a rabbit farm.
> As they observe the birth rates of the rabbits, they might figure
> out that those with the b-gene give birth more quickly.  When it
> comes time to kill a rabbit for its pelt, which rabbit will be the
> first to go?  I don't think it will be the rabbit with the highest
> birth rate.  I imagine rabbit farmers will come to value rabbits
> with higher birth rates and seek to protect them over others.

Unnatural, artificial selection, eh? :) Also interesting, though as
I stated, you'll really need to have genes that aren't all good or
all bad to posess.  Right now, there's no reason for a farmer not to
choose breeder rabbits.  It would be a lot more fun, IMHO if he had
to weigh price gained (at market say) vs. number produced, for

> Also, what if the utility of an animal increased with age?
> Suppose you might run accross young bucks, adult bucks, mature
> bucks, large bucks, and trophy bucks while hunting deer.  This
> might also provide an incentive to be more selective.  Especially
> if your community has noticed that the deer population is
> dwindling, and has decided to implement deer permits and quotas.
> The community might have an incentive to do this if they need to
> meet (character) population goals to level and are concerned that
> an ecosystem that is too out of whack may drive some players to
> other communities.

I don't think I'd have enough faith in a community to actually make
decisions like this.  Few people really have a group mentality
online, since the rewards are so imediate and the penalties not
real.  (Always comes back to griefers doesn't it? ;)

> In any case, that is the basic concept.  I'm not in any way
> committed to the actual numbers.  I think it would take a lot of
> experimentation to see what works best, but I don't see why the
> concept cannot be made to work.  I may have missed much, though.

It all depends on what you're trying to do.  Keep rabbits alive for
the sake of maintaining the ecosystem?  Maintaining a challenge for
ever-levelling-up characers?  Creating a simulation?  I agree
though, it *could* work.

Jasper "Asmaul" McChesney
jasperm at student.umass.edu / jasp at javanet.com
Historian, amateur scientist, recreational mathematician,
writer, thinker, game designer & artist.
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