Trampling

Currently, the word “trampling” is used to mean two different things:

• An attack type some monsters have and which has recently been filled with meaning: large enough creatures with AF_TRAMPLE (elephants and big dragons) will push their target back a square, and move into the square of their target. Players have this too in dragon form. Test!
• A size-dependent ability for monsters (and players) to quickly dispatch (i.e. trample) much smaller monsters. This idea is discussed here.

It may be best to rename AF_TRAMPLE to AF_KNOCKBACK.

Mechanic conceived on ##crawl by keskitalo:

20:24 < Keskitalo> We should let large monsters trample small enemies, i.e. if 
                   they kill it, they get a free move if they were going to the 
                   same direction.

Subsequent discussion provided the following finer points:

• Crawl has the following sizes: TINY, LITTLE, SMALL, MEDIUM, LARGE, BIG, GIANT, HUGE. A creature (monster or player) attacking a creature three or more levels smaller can trample it (this should presumably depend on something), e.g. a medium sized creature (human) could try to trample a tiny creature (rat). Bat is also tiny, but flies. (A dragon is huge and could trample ogres, trolls, nagas, centaurs.)
• A creature that successfully tramples can take an immediate step in that direction (i.e. on the presently liberated cell). It would do so only if that spot is desirable.

Amulet of Stasis should probably prevent being pushed away. I'm a bit uncomfortable with it because it's a physical effect, but since the amulet already prevents physical berserk (being pissed off) then it's already too late. Am I right both Clarity and Stasis prevent all sorts of berserk ? — b0rsuk 2010-09-07 19:57

Player berserk is anything but physical, and it's hard to see what an amulet that concerns itself with things like enchantments and translocations is going to do about getting rammed by several tons of elephant. — og17 2010-09-07 21:08

By extension, it would be cool to have players trampling as well. Some issues:

• Interface: players will want to use the trample effect sometimes but not nearly always. Also, you may not get the trampling effect every time you attack a rat (so the player cannot plan (and press keys!) in advance).
• Species diversification: Large species (ogres, trolls, centaurs, nagas) get the advantage to trample little monsters — but this is mostly nominal (there are few little monsters).

Why do we want player trampling in the first place? It's cool, sure but it also

• makes smallish showstoppers less reliable (on D:4, hiding behind a rat in a corridor will work — not so in Vaults)
• has an effect on spells (Summon Small Mammals suffers, Dragon Form gains)
• may be tactically interesting at times for the player

Eventually, we may move this page to the weapon move page Combat Maneuvers & Weapon Reform — it is similar in spirit to sidestep, I think.

Obviously, if player trampling makes it into the game (and perhaps already when monster trampling appears), we will want to list sizes in monster description. And looking at a monster could add a line like You can possibly trample this monster.

A prompt Do you want to trample the rat? (y/n) is out of the question. Instead:

• Free second move: In case you trampled something, the (just liberated) cell should be very visibly highlighted; we may also want to issue a message. Pressing some key (e.g. Space) will walk there instantly. (We want players mindlessly bashing arrow keys not be surprised by getting odd moves.)
• Automated trampling: One could think of immediately moving the player onto that cell. For this, the normal attack method (arrow key) should forfeit all tramplings; another attack method (candidates would be Shift-direction or Ctrl-direction) would take the trample opporunities.
• Prescient trampling: Not all potentially trampling-eligible attacks will lead to trampling (no matter if monster/monster or player/monster). We could indicate a trampable monsters in advance, e.g. by some brand. In other words, instead of rolling whether trampling occurs after the attack has been initiated, we do it before the move (for all adjacent monsters). There would still be the need for two different modes of attacking (as above), but it would play much smoother, I hope. — dpeg 2010-09-07 00:12

Regarding the comments the first installment of this page, it seems highly desirable to make plain meleers to play exactly the same as they do know: no surprises, no forced moves.

It is not really clear whether we need all eight size types (although the system is appreciably coarse already). og17 suggests to only use five steps (tiny, small, medium, big, huge) and have trampling occur at two sizes difference (perhaps with a special rule: tiny being trampled by everything larger, and huge trampling everything smaller).

evtkalo suggests that only large player species get the trample benefits. This would make them stand out much more, but cause inconsistencies (monster orcs can trample rats, player orcs can't). This will inevitably draw many complaints, even if it turns out to be the best solution gameplay-wise.

It would be possible to make the matter a bit more complicated by taking monster/player shape into account. (So nagas would have fewer trampling opportunities than trolls). For monsters it is not that bad, they could simply get a trampling parameter. A simple solution for player species that dpeg likes is to link chance of trampling to innate (no modifiers) Strength. Together with size, this could make trolls and ogres significantly better tramplers than their peers.

zannick 2010-08-25 05:25: I am not sure anyone has suggested exactly this trample idea: Why just for monsters attacking enemies? For example, if a rat is between a player and an ogre in a corridor, with both the rat and ogre hostile to the player, the ogre, who presumably doesn't care at all about the rat, could just step on it to get next to the player, perhaps killing it, or injuring it and forcing it behind the ogre. In short, large enough creatures ignore the presence of the really small ones and step on them.

I was going to write this in a dedicated “Sizes” page, but I'm not ready yet. I have a similar idea: size allows to shoot and cast spells over smaller monsters. This would mean tall monsters can shoot over smaller ones. It works both ways - ogre conjurers or throwers could fire at dangerous monsters in a crowd, but would also be more at risk. I need to think about the specifics, formula etc. — b0rsuk 2010-08-07 18:23

“Trample” is already well-used; I would suggest borrowing a term like 'overrun' or 'overwhelm' from wargaming instead.