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Author Topic: Why does the corner trick work?  (Read 5431 times)

Adam Bomb

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Why does the corner trick work?
« on: January 27, 2010, 09:15 »

By corner trick, I mean getting into this kind of position:
Code: [Select]
.......B
.@.#####

When you are in this position, you can shoot the enemy, but they won't shoot back. I assume the reason is that the enemy's LOS is blocked by the wall, but if that's true, I don't understand why, because if I stand where the B is, I can shoot that location around the corner. Can anyone explain this to me? It seems like the corner trick is an exploit of a LOS bug; is it? Or is this behavior intentional and designed?
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Kornel Kisielewicz

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Re: Why does the corner trick work?
« Reply #1 on: January 27, 2010, 09:37 »

LOS bug. To be fixed in 0.9.9.2
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Adam Bomb

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Re: Why does the corner trick work?
« Reply #2 on: January 27, 2010, 10:07 »

Good, now I know not to rely on it. Thanks, Kornel!
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thelaptop

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Re: Why does the corner trick work?
« Reply #3 on: January 27, 2010, 10:15 »

Good, now I know not to rely on it. Thanks, Kornel!
No no no... rely on it now, but be aware that it will be fixed (i.e. relearnt) in the future.

(=
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Sylph

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Re: Why does the corner trick work?
« Reply #4 on: January 27, 2010, 11:18 »

I thought this just represented the ability to stick your arm out around the side of a wall without exposing yourself....

If this is getting fixed, where will the tactics in doomrl lie? I often mention this feature, when talking doomrl up to my friends, as the sole reason doomrl is such a tactical game - without it surely doomrl would just be about having enough health and armour to out-tank opponents?
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Midnight

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Re: Why does the corner trick work?
« Reply #5 on: January 27, 2010, 11:28 »

Yeah, I think so too. Corner trick is probably the only way of dealing with superior enemies early on (except the acid/lava fields usage, but that depends too much on level generation), and surely it's the only way to deal with knights/barons without losing health. A vote is in order, perhaps?
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Adam Bomb

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Re: Why does the corner trick work?
« Reply #6 on: January 27, 2010, 11:55 »

I disagree with the above two posts stating that the corner trick is desirable. If you can see an enemy, they should be able to see you. I should clarify that when I say "corner trick" I do NOT mean firing into blind spots to hit unseen enemies. I mean standing in special spots where you CAN see the enemy to exploit the algorithms that plot the paths of missiles so that your line of fire is clear, but the enemy's return line of fire is obstructed.

Removing the corner trick will not remove tactics from the game. For example, you will still be able to:
1. Shoot enemies that you cannot see (and cannot see you) but are in areas you can still target (e.g. shooting into the blind spots of obstacles or beyond 8 spaces)
2. Trap enemies behind acid/lava and shoot them from out of sight
3. Knock enemies into acid/lava
4. Lure enemies near barrels and use the explosion(s) to kill them
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Midnight

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Re: Why does the corner trick work?
« Reply #7 on: January 27, 2010, 12:46 »

Allow me to disagree, too. Corner trick represents, like Sylph said, the ability to shoot out of cover. Moreover, while removing it does not equal total removal of tactics from the game, it does remove a lions chunk of it. Let's analise your proposed tactical points:

1: Shooting enemies out of LOS, while a viable tactic, incurs accuracy penalty. Consider the folowing situation:

           B
@#####

The knight will come into view within one or two moves. If corner trick is removed, it will then proceed to fire immediately. This means that the player has only two shots at most, each with additional acc. penalties, to make before he starts to get damaged - and that's almost never enough. And, considering that all B's are telepathic monsters (they know where you are even if they don't see), the player will have no way of outmaneuvering the knight - so he WILL get damaged, no matter what he does.

2,3: Requires some RNG love, so it's not really a tactic per se.

4: A barrel blast is never enough to kill tougher enemies. So it's the same as 1.


Also, consider this points:
1. Removal of any tactical tricks the player has, will, ultimately, only make the gameplay poorer.

2. The corner trick is deeply ingrained into the mind of DoomRL players - suffice to say it is featured in both FAQ's I have read as primary advice for beginning players.

All in all, I think that if such a change is to be made, a vote is in order.   
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Adam Bomb

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Re: Why does the corner trick work?
« Reply #8 on: January 27, 2010, 13:56 »

Allow me to respectfully dispute your points

1: Shooting enemies out of LOS, while a viable tactic, incurs accuracy penalty. Consider the folowing situation:

           B
@#####

The knight will come into view within one or two moves. If corner trick is removed, it will then proceed to fire immediately. This means that the player has only two shots at most, each with additional acc. penalties, to make before he starts to get damaged - and that's almost never enough. And, considering that all B's are telepathic monsters (they know where you are even if they don't see), the player will have no way of outmaneuvering the knight - so he WILL get damaged, no matter what he does.
There are ways to avoid getting damaged in this situation.
1. Double shotgun blast to knock the enemy back out of sight
2. If it's a thin wall, run around to the other side. The enemy will attempt to follow you in a straight line instead of going around the wall. You can use this technique to reset or maneuver them into another advantageous position. Or, now that you know where they are, you can stack up multiple barrels on the other side, then stand back and blow them away in a magnificent chain reaction. :)

2,3: Requires some RNG love, so it's not really a tactic per se.
Acid/Napalm barrels are extremely common, and a reliable way to create acid/lava barriers wherever you want them. The RNG might hold out on you occasionally, but it's far more likely that you'll have the means to create a lake of corrosive/fiery death

4: A barrel blast is never enough to kill tougher enemies. So it's the same as 1.
So, make a trap consisting of several that will cause a chain reaction.

Also, consider this points:
1. Removal of any tactical tricks the player has, will, ultimately, only make the gameplay poorer.
It should be quite clear by now why I disagree with this assertion. There are plenty of tactical options remaining to the player without exploiting a bug.

2. The corner trick is deeply ingrained into the mind of DoomRL players - suffice to say it is featured in both FAQ's I have read as primary advice for beginning players.
It's a bug. If it's intentional behavior, then it should be documented in the game's help.

All in all, I think that if such a change is to be made, a vote is in order.   
A vote is only relevant if DoomRL is the community's property. I don't know whether Kornel views DoomRL as the community's property or his own. I do think it would be presumptive to assume that DoomRL is the community's property without his say-so. As such, I think that he should be able to do whatever he wishes with his own creation, doubly so when it comes to fixing bugs.
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Midnight

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Re: Why does the corner trick work?
« Reply #9 on: January 27, 2010, 14:37 »

Allow me to disagree, again:

1. Shotguns will keep that knight at bay for only so long, and he only needs to make two moves to come into firing range. Shotguns, on the other hand, suffer damage reduction with range. Also, knockback is not that great on heavier targets, either.
As for barrels - their stacking can and usually will backfire in the worst possible way. Not to mention it's not at all viable.

2&3. While yes, lava/acid barrels are common, you are not always presented with a chance to use them in the intended way, and obviously, you can't deal with all encounters in such a manner (although I have to say that such tactics are one of my favourites in dealing with tougher enemies in mid to late game). 

Quote
It's a bug. If it's intentional behavior, then it should be documented in the game's help.

Not all features are documented in most programmes - DoomRL is no exception. Actually, most of it's features are not documented and have to be learnt by experience (although I haven't checked the help file lately, maybe it has been expanded) .

Quote
It should be quite clear by now why I disagree with this assertion. There are plenty of tactical options remaining to the player without exploiting a bug.

Tactical choices remain, yes. But doesn't more choices mean deeper and ultimately more rewarding gameplay experience?

Quote
A vote is only relevant if DoomRL is the community's property...As such, I think that he should be able to do whatever he wishes with his own creation, doubly so when it comes to fixing bugs.

Of course, only Kornel decides whether features get implemented or not. But DoomRL has a history of developing through players feedback, so why not discuss the corner trick?


In any case, I've decided to do some test runs and see if I can deal with HMP midgame without the corner trick. I'll post results later.
« Last Edit: January 27, 2010, 14:43 by Midnight »
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Tavana

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Re: Why does the corner trick work?
« Reply #10 on: January 27, 2010, 15:43 »

For the record, I don't knowingly exploit the corner trick, and have beaten both HMP and UV. It can be done.

Perhaps whenif it gets taken out via improvement of the LOS algorithm, something else can be implimented in its place? Like leaning around corners?
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danabnormal

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Re: Why does the corner trick work?
« Reply #11 on: January 28, 2010, 08:15 »

Hmm.. I think the removal of corner trick will make DoomRL more frustating and less fun. It's a bug but it adds something interesting into gameplay. But I agree with fixing it in the next release. We can test it, and may be we'll find some new strategy/gameplay. If the community dislikes it, we can ask Kornel to bring the corner trick back.
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Frankosity

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Re: Why does the corner trick work?
« Reply #12 on: January 28, 2010, 10:24 »

I'd honestly prefer it if the game rewarded agility over the ability to sit on a corner and exploit a line-of-fire bug. It's a bit tangential to the topic, but I'd be interested to see a Gun Kata-style bonus after a successful dodge, encouraging players to behave more agressively.
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yns88

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Re: Why does the corner trick work?
« Reply #13 on: January 28, 2010, 12:24 »

The way I see it, if you're corner-shooting from cover, you should expect to either:

A) Take the risk of being targeted by your enemy, or
B) Incur a penalty to your ability to fire accurately.

There's no way to realistically fire accurately around a corner without your opponent spotting you.

Maybe with the removal of the LOS bug you can add a feature such that if you're standing next to a wall and a bullet passes diagonally through that wall to hit you, you gain a "cover defense" chance of the bullet bouncing off the wall.

Here's an example:
Code: [Select]
.......
..@....
###....
..#,...
..#,,..
..#,,..
..#,,,.

The commas would mark locations of monsters that you gain a "cover defense" bonus against.
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Thomas

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Re: Why does the corner trick work?
« Reply #14 on: January 28, 2010, 16:54 »

For the record, I don't knowingly exploit the corner trick, and have beaten both HMP and UV. It can be done.

Surely Hell's Arena would be impossible on HMP or UV without the corner trick. (And beating the game without going there is rather challenging)

As for the removal of the corner trick, which I am all for, I think it's going to have a huge effect on the game difficulty and will certainly need to be implemented simultaneously with something that makes the game easier.

I'd honestly prefer it if the game rewarded agility over the ability to sit on a corner and exploit a line-of-fire bug. It's a bit tangential to the topic, but I'd be interested to see a Gun Kata-style bonus after a successful dodge, encouraging players to behave more agressively.

This is a good idea, or we could just reduce fire times in general and make reloading the primary time-management problem.
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Arch-Vile Chaos Major Thomas
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Tavana

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Re: Why does the corner trick work?
« Reply #15 on: January 29, 2010, 04:46 »

HMP Arena will kill you a few times without using it, yes.

UV Arena will kill you a few more times without using it.

"Suck it up and survive." =P

That being said, I agree with Thomas. Currently, most players require the use of the corner trick to go far in the game. And the game isn't that fun to play if you can't win every once in awhile. To be honest, if the standard game was easier, you might even get a few more players, and the Challenges would feel more "fun", as they're making a game that isn't TOO hard to beat up to the level that it is at now. Then again, there are those that simply excel at the game. For them, we can always implement another difficulty level. ;)
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Frankosity

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Re: Why does the corner trick work?
« Reply #16 on: January 29, 2010, 10:46 »

People don't play roguelikes because they're easy to beat. If people aren't playing DoomRL because it's 'too hard' (which it really isn't at ITYTD or HNTR) then they're not the target audience for the game.

It remains to be seen how much harder the game will be after the bug is fixed. Reminder that it was affecting the player as well, potentiall making the game easier in some aspects.
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yns88

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Re: Why does the corner trick work?
« Reply #17 on: January 29, 2010, 20:19 »

To be honest, if the standard game was easier, you might even get a few more players, and the Challenges would feel more "fun", as they're making a game that isn't TOO hard to beat up to the level that it is at now.
The problem that I'm seeing is that since corner shooting is an exploit strategy that only experienced players understand, it's actually serving as part of the barrier to new players. Even after reading a guide about it, I still don't usually know when I'm playing whether a monster can see me or not (or whether my shotgun can hit them or not due to the shotgun corner bug).

There's nothing wrong IMO with the gameplay concept of using a corner as cover, I just think it should be legitimized and made easier to understand. That's what I like about DoomRL: most of the gameplay is simple and easy to understand, and yet it's probably the most skill-based roguelike I've played.
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Thomas

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Re: Why does the corner trick work?
« Reply #18 on: January 30, 2010, 16:10 »

It remains to be seen how much harder the game will be after the bug is fixed. Reminder that it was affecting the player as well, potentiall making the game easier in some aspects.

Pfft, anyone actively looking for chances to do the corner trick (myself included) will use the trick 100 times for every one time it's used against them.

The problem that I'm seeing is that since corner shooting is an exploit strategy that only experienced players understand, it's actually serving as part of the barrier to new players. Even after reading a guide about it, I still don't usually know when I'm playing whether a monster can see me or not (or whether my shotgun can hit them or not due to the shotgun corner bug).

There's nothing wrong IMO with the gameplay concept of using a corner as cover, I just think it should be legitimized and made easier to understand. That's what I like about DoomRL: most of the gameplay is simple and easy to understand, and yet it's probably the most skill-based roguelike I've played.

This raises an interesting point. The corner trick is quite difficult to explain (one can only provide examples and hope the player gets the general idea from there) and the ability to recognise when corner tricks will work is an example of something that seperates an excellent player from a good player, just like being able to recognise when it's possible to sprint for a berserk pack on 10% HP or whether you'll need to heal first.

Replacing it with a flat bonus such as decreasing default fire-delay to 0.5s for the player, assuming that flat bonus is just as handy as the corner trick, will remove one of the skills that almost every excellent player uses and replace it with something everybody will use regardless of whether they know about it, shallowing the difficulty curve somewhat.
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Arch-Vile Chaos Major Thomas
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yns88

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Re: Why does the corner trick work?
« Reply #19 on: January 30, 2010, 21:34 »

Replacing it with a flat bonus such as decreasing default fire-delay to 0.5s for the player, assuming that flat bonus is just as handy as the corner trick, will remove one of the skills that almost every excellent player uses and replace it with something everybody will use regardless of whether they know about it, shallowing the difficulty curve somewhat.

This is not necessarily true. What I've been proposing still requires tactical positioning by having the doomguy stand behind barriers. A novice player would do it accidentally, an experienced player would start hugging corners, and an excellent player would take advantage of the map layout and monster AI to herd monsters into locations where he could gain a cover bonus against them.
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