[Crawl-ref-discuss] Dynamical monsters: monster upgrades

[David P. <dp...@ma...>]

Dynamical monsters
==================

This text sounds theory-crafting: I am thinking about Crawl like a board 
game, and want to make its ruleset more flexible. I have concrete 
applications in mind. Was waiting for a good opportunity to send this out; 
Corin's email is triggering this posting.


Current situation: monsters are static
======================================

What I mean by this: monsters are the backbone of Crawl's gameplay. 
Players are dealing with them all the time (even when choosing not to 
fight some monster), and monsters provide most of the relevant reward 
(experience, and often piety), and protect a lot of the item loot.

Right now, monsters are generated when the player enters a level. After 
that, almost nothing happens to them. Monsters can get added through extra 
generation and in very few other ways. Monsters can disappear by killing 
(most often), or in some more exotic ways (shafts, banishment). Most 
importantly to me, monsters that have been generated will not change 
afterwards. This is what I mean by "static", and I suggest we make them 
more dynamical.


Dynamical monsters: self-changing and self-removing
===================================================

In my opinion, it will be useful to have a system where monsters can 
change or disappear. Let me start with the latter:

Disappearing monsters
---------------------
I'll suggest a pretty simple mechanic and argue for it afterwards.
* Mechanics: Whenever you re-enter a level, the game looks at all
   monsters. A monster will be removed if it is considered to be no
   valuable threat anymore.
   If this happens: no message, and no compensation for food/xp/piety.
   Uniques are exempt. Vault monsters can be exempted by tags.
* Reason 1: Players can, and sometimes do, park harmless monsters for
             food or piety. (Death) yaks in Lair are an example.
   Reason 2: If you want to make sure that you get to collect all the
             xp/piety off a level, you have to refrain from skipping
             it for a while.
   Reason 3: It's not interesting to chase subpar monsters, just tedious.


Upgrading monsters
------------------
This is the more adventurous part of my proposal: I'd like monsters to get 
the ability to "upgrade", i.e. become stronger than originally created.

* Mechanics 1: monsters can upgrade, and can do so several times. This
   will be indicated by an adjective to the name, such as
      orc --> angry orc --> very angry orc
   Perhaps other adjectives work better, e.g.: fierce, grim, monstrous.
   Have to avoid reference to berserk rage (e.g. furious or mad).
   Each upgrade will apply the following modifications:
    - movement and action speed faster by 2
    - HP increased by 20%
    - HD increased by 20%
    - base damage increased by 20%
   There is *no* change to experience value, piety gain, items!
* Mechanics 2: I have two triggers in mind, the first one is more
   important to me.
    - For each monster, count time when it is aware of you.
      Have it upgrade as a function of that time. [0]
    - For each monster, count its time since generation. [1]
      Upgrade it as a function of that time.
      (These two functions would be different.)
* Analysis:
    - An immediate application of monsters upgrading when aware of you: we
      can get rid of energy randomisation. This was introduced to deal with
      pillar dancing, but monster upgrades do so in a better way: instead
      of monsters getting an additional move at random, you now see an
      actual change (such as "orc" --> "angry orc"), so the interface is
      much more clear.
    - My original motivation, however, is luring: that tactic would be
      alright if it was special. But it's not, rather it is ubiquitious,
      slow and tedious. On the other hand, I don't want to make players
      unable to flee from dangerous situations. Monster upgrades is a
      rather mild counter to that: if you lure a lot, then your battles
      will be a bit harder. [2]
    - This change does not really affect weak players, say naive newbies:
      they will attempt to clear levels, and walk towards monsters anyway.
      I like that: this nerf shouldn't make their games more miserable.


Full disclosure: this idea has been inpired by Brogue's monster mutations 
and by promotions in Japanese chess (Shogi). (In Brogue, a monster can get 
generated with special perks, e.g. "reflective ogre" and this is indicated 
by an adjective. Note that Brogue's mutations are static: bestowed on 
monster generation.)


If we like monster upgrades, then a whole lot more could be done. This is 
a barebone proposal.



[0] I thought about this for a while, and think it's the best approach. 
Originally, I tried to measure "monster follows player", i.e. to gauge 
luring-ness. But that's hard. Much better to just make it a function of 
how long the monster is aware of you. Yes, sometimes you will get unlucky, 
and that orc turns into an angry orc right away. I think that's definitely 
worth the gain in simplicity. If we feel generous, then we can announce 
the change a few turns in advance: "The orc looks like it is getting 
angry."

[1] There are two versions of this:
     (a) count total time since monster generation (player on level or not).
     (b) only count time spent by the player on the monster's level.
With (a), you would know that entering a level, fleeing and coming back 
much later (think of a branch end you got chased away from) will have many 
monsters which are much stronger. That's a strategical monster/level buff, 
and I am fine with that. It would also mean that players are encouraged to 
try and pull through a level they enter or, put the other way around, 
enter levels conservatively. With the level cutting policy we've been 
carrying out since DCSS 0.4, I'm also fine with that, but I realise not 
everyone might be. (And it will draw complaints such as: "I stepped foot 
into Elf:1, was scared by the entrance party, and came back to realise 
they're even stronger." I'm ready to shrug that off because the player is 
also stronger by then.)
   By contrast, (b) only punishes dawdling on a fixed level.

[2] Luring is also about waking monsters one by one. My proposal 
purposefully says nothing about this (that'd involve noise and monster 
AI). I think monster upgrades are a good addition in their own right, and 
I believe that it's better to treat design concepts as separately as 
possible.