Insta-killing bosses by getting them stuck

[sigsegv [the real one]]

A lot of experienced players already know about this, but I caught a nice video of it that I thought some people might want to look at.

If you get a robot stuck in a particular spot for long enough, the game engine will try to get them un-stuck at first, but eventually, it will just give up and kill the robot. Which I guess solves the "being stuck" problem, in a certain sense (in the same dubious sense as killing a cancer patient technically solves their cancer problem).

https://www.youtube.com/watch?v=ne0V1igicY8

Watch the boss's health meter. He goes directly from ~50% health to dead, instantly.

Seems to be easier with demoknight's push force reduction upgrade and uber canteens. Having a player on each side of the robot probably makes this more likely to happen because he gets sandwiched and can't move in either direction to get un-stuck.

[NighT WolF]

Thought it would already been fixed. Such a bug was in mvm years ago and was very easy to execute.

http://steamcommunity.com/sharedfiles/filedetails/?id=269161262

[sigsegv [the real one]]

Originally posted by NighT WolF:

Thought it would already been fixed. Such a bug was in mvm years ago and was very easy to execute.

Yeah I think there have been a number of "fixes" from Valve over the years that haven't really solved the root cause of the problem.

Take, for example, the nerf that made giants detect spies and shoot them if they block for 5 seconds. That definitely makes it harder to block continuously; but as long as you don't die and you keep them stuck for long enough, you'll still eventually trigger the "kill because stuck" code in the game.

Uber demoknight with max resists, minimal push force, uber canteens, etc. is basically the best possible scenario for blocking the giant for so long that he can't make you die or push you out of the way at all. (I believe there's basically a timer that counts how long the robot has been stuck, and if it gets to some value, it kills the robot; if he can push you out of the way for even a moment, then that counter resets.)

A possible fix for this exploit would be to just get rid of the "kill because stuck" logic entirely, at least for giants/bosses. Presumably that logic is in there in the first place because bots will get stuck in rare cases and they want to avoid stuff like the mission being unbeatable because a bot is stuck in the spawn zone where it can't be killed, or something. And they added the stupid engie airblast thing which is an apparent attempt to prevent players from getting stuck in engie buildings, which is sort of related.

If Valve were to ever fix this, I can just imagine them releasing an update with patch notes that say

fixed an exploit related to MvM giants

where they just take bodyblocking out of the game entirely because they're too dumb to figure out how to actually fix the problem properly.

[itsgalf]

Had it happen on Sergeant Crits not too long ago. But instead I caught him as demoknight right when he walked out of spawn. I think heavy raged him on the slight downslope causing him to be airborn and he hit the nearby wall. I bodyblocked him so he wasn't able to drop down to the ground...he floated for a few seconds...and then blew up.

All in about 6 seconds. Fastest Wave 7 I've seen.

[sigsegv [the real one]]

Originally posted by itsgalf:

Had it happen on Sergeant Crits not too long ago. But instead I caught him as demoknight right when he walked out of spawn. I think heavy raged him on the slight downslope causing him to be airborn and he hit the nearby wall. I bodyblocked him so he wasn't able to drop down to the ground...he floated for a few seconds...and then blew up.

All in about 6 seconds. Fastest Wave 7 I've seen.

Did you get stuck inside of him? I've had that happen as demoknight a couple of times. Got completely stuck, boss suicided a few seconds later.

[itsgalf]

Don't think so. He was airborn, raged against the wall. I blocked him so he couldn't drop and he floated there for a few seconds. then KABOOM

[Soldier Claus]

Captain Punch got stuck on the big rock in the corner of the cave once on one of my first Bone Shaker runs. I'm pretty sure he just died because we had forever to kill him, not because he exploded.

Also, doesn't work on bots still in spawn.

Basically, nice failsafe, Valve.

[itsgalf]

Have you noticed that when you get get 'stuck' inside Sergeant Crits he loses his ability to fire bursts? I've had a few times where he seems to be confused and doesn't shoot bursts anymore. I'll take 1 burst of damage and then a long pause before the next one. Meanwhile my +10 passive regen brings me back to full health

[EyeOculus]

Sometimes, if Sire Nukesalot is stuck, he will get teleportet back.

[Radioactive Panda]

that seems to be terrain. I haven't seen him do it when he gets stuck in a player. Granted never tried.

[sigsegv [the real one]]

It's pretty easy to get a robot stuck on an object if you use the nb_select/nb_warp_selected_here commands I showed in this post.

Seems to be handled differently from when a bot gets stuck in a player. Here's what the console says when I warp a robot so that it's stuck on an object:

02/21/2015 - 11:51:19: Robot's getting stuck with worldspawn
02/21/2015 - 11:51:19: Robot's getting stuck with worldspawn
02/21/2015 - 11:51:19: Robot's getting stuck with worldspawn
02/21/2015 - 11:51:19: Robot's getting stuck with worldspawn
02/21/2015 - 11:51:19: Robot's getting stuck with worldspawn
02/21/2015 - 11:51:19: Robot's getting stuck with worldspawn
02/21/2015 - 11:51:19: Robot's getting stuck with worldspawn
02/21/2015 - 11:51:19: Robot's getting stuck with worldspawn
02/21/2015 - 11:51:19: 387.27: A robot is interpenetrating a solid - killed!
02/21/2015 - 11:51:19: player taking damage from player, via player. Damage: 999999.88
02/21/2015 - 11:51:19: Dropped flag trace started solid!
Wiggle around each axis to find a safer fit!
02/21/2015 - 11:51:19: Couldn't find a safe place to drop the flag!
Dropping at the player's center!
02/21/2015 - 11:51:19:     DEALT: Player took 999999.88 damage.
02/21/2015 - 11:51:19:     HEALTH LEFT: 0
02/21/2015 - 11:51:19: Giant Heavy suicided.

[Hacked Exhale]

Robots will suicide if they can't change their Y or X axis in any way or form. The suicide timer is restarted if they manage to take 1 step in any direction but jumping also resets it, since it still counts as changing their position.

You have to get them completely stuck for them to suicide. Doesn't matter if they are airborne or on the ground.

Merging with the mecha bosses was piss easy back when mecha first came out but they made it harder to do later on.

Originally posted by itsgalf:

Have you noticed that when you get get 'stuck' inside Sergeant Crits he loses his ability to fire bursts? I've had a few times where he seems to be confused and doesn't shoot bursts anymore. I'll take 1 burst of damage and then a long pause before the next one. Meanwhile my +10 passive regen brings me back to full health

That happens with all soldier bots. They are programmed to not shoot targets that are right in their face, because they will take self damage. I am pretty sure they are suppose to whip out another weapon and do damage with that instead but since they are forced to use their primary they just stare at you.

They have to make a very tiny gap between the target and them before they will shoot, either by walking around but usually by jumping.

[sigsegv [the real one]]

Originally posted by Hacked Exhale:

That happens with all soldier bots. They are programmed to not shoot targets that are right in their face, because they will take self damage. I am pretty sure they are suppose to whip out another weapon and do damage with that instead but since they are forced to use their primary they just stare at you.

They have to make a very tiny gap between the target and them before they will shoot, either by walking around but usually by jumping.

And then they still die from self-blast damage in many cases.

At least the poor bots are trying their best to avoid it.

[sigsegv [the real one]]

I found another interesting tidbit.

Most people already know that bots can take fall damage

• because you can rage giants into the air to make them take damage when they fall
  
• because it explains why money sometimes drops in the robot spawn zone

When robots drop in from spawn (on maps where they have to drop down to enter the main area), tf_debug_damgae 1 reveals that they take fall damage:

02/21/2015 - 11:51:57: player taking damage from worldspawn, via worldspawn. Damage: 821.60

But because the spawn-protection uber effect wears off after they finally touch the ground of the main area, they don't actually take damage.

[Hell-met]

bot merge used to happen about 1/2 time with old spy disguises (no detection with touch)

it took me a while to learn how to kill captain punch legit

there's a second failsafe where if a bot is airborne for too long, it will automatically teleport back to the last known grounded position. but that's pretty much impossible to replicate in valve's maps

[sigsegv [the real one]]

I found a relevant cvar for this: tf_resolve_stuck_players.

It's 1 by default; set it to 0 and stuck robots won't self-destruct, no matter how long they are stuck for.

https://www.youtube.com/watch?v=pF4p3dOB1vs

If a robot is stuck for a while with the cvar set to 0, and then you set it to 1, they will immediately self-destruct right after you enter the command.