BHVR is neglecting hybrid control schemes accessibility and exploits

Hi,

This discussion surrounds a bug that was seemingly introduced around the release of the Trickster (Mar 2021, 4.6.0), that BHVR has acknowledged and neglected to fix. This bug causes 3 main problems: FPS drops, missed inputs and update suppression. It is caused by using hybrid control schemes (controller joystick + mouse input)

The update suppression feature of this bug enables exploits such as these:

• Stun invulnerability - forum post
• Walking through the exit gates (last section) - forum post

If you've ever seen something similar happen in your games, this might have been at play, given people know of this mechanic.

Stun invulnerability - Update suppression

The stun invulnerability clip was from the first game I tried joystick movement on killer, and the bug occurred multiple times, meaning it is reproduceable. As soon as it happened, I knew what was going on, given I'd seen the youtube short above about the exit gates. (I've previously only been using joystick on survivor, where this specific issue hasn't occurred)

In short, the bug occurs because the game is continuously switching between control schemes (controller/KB&M), because both are analog inputs. When this updates every frame (as seen by the glyphs changing), it suppresses/stalls inputs from the game. This only effects updates that are client-sided, which we of course know is authoritative over a lot of game events.

See under for suggested fixes for this bug.

Accessibility - FPS and input impact

Outside of the exploitable effects of this bug, it has had a major effect on accessibility. A lot of people, for different reasons, can't optimally play DBD and other games using keyboard. When this bug was introduced, multiple people reported it on the forums (see under).

Given that the engine is seemingly updating control schemes every frame, which can cause severe FPS drops, meaning using hybrid control schemes isn't an accessibility option. (This may have improved in recent updates, although my PC has been upgraded)

Even without the FPS issues, the game is unable to pick up inputs from both control schemes at the same time. This means that if you try to use a keyboard binding while the control scheme is detecting controller, the input will be ignored until the next frame when it switches to keyboard, in which you'll have to press it again.

So if you are moving with an analog stick and looking around at the same time, you can't consistently use a digital input (key or controller button presses).

BHVR neglect

This issue is not new, even to BHVR. Here is a list I made (over a year) ago compiling all the forum posts I could find discussing this issue:

• Hybrid input (Analogue controller + Mouse/Keyboard) bug: first input consumed, action doesn't happen (Marked Under Review Sep 2023)
• PC - When using controller and mouse together, certain inputs do not work properly anymore (Nov 2022)
• more optimisation for people who play controller/mouse (Sep 2022)
• DEVELOPER HELP Using controller and mouse simultaneously drops FPS massively (Marked Acknowledged Jun 2021)
• Game's frames drop drastically when trying to use both mouse and controller (Mar 2024)
• Using mouse and gamepad controls simultaneously causes massive performance drops. (Apr 2021)
• So I’m a duel controller player: use mouse and controller- and it won’t let me use dead hard. (Jan 2023)
• Controller and mouse problem (Marked Duplicate May 2021)
• Another bugfix patch released and no fix on Fps drops while using controller and mouse at same time. (Marked Duplicate May 2021)
• Unable to use ability when playing with controller and mouse (Dec 2022)
• DH and sometimes vaulting is still broken whilst being a controller and mouse player. (Feb 2023)
• Playing with controller and mouse at the same time causing massive frame drops (Accessibility) (Aug 2021)
• PC - Controller + Mouse input still causing FPS drops (Jul 2021)
• Ongoing SEVERE fps drops when using controller and mouse simultaneously (Apr 2021)
• Framerate drops while using Controller + Mouse (Commented on by Community Manager May 2021)
• Significant FPS drops still occurring while using gamepad and mouse simultaneously (Jul 2021)
• PC Significant FPS drops still occurring while using gamepad and mouse together (Sep 2021)

As seen here, the issues related to FPS has been acknowledged since 2021, while issues of input problems have been under review for 2 years.

I've personally sent support tickets to have this looked at, but also more specifically, for it to be added to the Known Issues section of the forums. If you check as of now, it has not. The issue request contained the above list, a detail description of the problem (not update suppression), a description of the impact, along with descriptions of how other games deals with these issues.

The responses were, in brief, that:

• No timeline can be given, but they can assure they will be looking into it (Oct 11, 2024)
• (After a follow up re-requesting for it to be added to the known issues) "Also, about your quest for this bug to be set in the Know Issue section of forum, we'll take a look at it but we can guarantee that this change will be made." (Oct 30, 2024) (may have been a typo, I guess?)
• (after a follow up) "Regarding the case being added to the known issues in the forum despite what you were informed before, we can't guarantee it'll be added to that section at any specific moment." (Jan 28, 2025)

I genuinely believe the people who work at BHVR are well meaning and want this fixed. My assumption is that profit motives muddle that process and administration in general. I am not holding any individual accountable for this issue not getting allocated resources.

Fixes

This issue is common in many more games than DBD, and not all allocate the resources to handle it.

When the problem is limited to the glyphs changing upon hybrid controls being used, one common fix is to enable a setting that restricts the glyphs to a specific control scheme. (Picking KB&M, for example)

This might not work cleanly in DBD, given that the game is clearly switching between modes where the other control scheme stops being monitored. For a hybrid control scheme to work here, an option may need to be added and implemented to allow multiple input types to work simultaneously, on top of specifying which control scheme's glyphs should be displayed.

These fixes may not address the crucial part of this bug, which is the update suppression. They have to stop the updating of control schemes to suppress game updates. To get it out of the way, this can be mitigated by tackling client side authority by means of server side validation. The client shouldn't be in charge of whether or not a stun occurs. (this is a general solution though)

To tackle the issue specifically, they can tweak the engine to not suppress updates upon switching of control schemes. Ideally though, they should make it so that multiple control schemes could be used at once, and dynamically add whichever is detected to the list of monitored/accepted inputs. This would fix the other issues except for the changing glyphs, which can be fixed with an option to lock one control scheme.

Another great change that would assist in accessibility and fix exploiting, is to make analog inputs non-exclusive to control schemes, meaning that analog stick movement and mouse movement is accepted by both KB&M and controller control schemes (so that only key or button presses switch modes). This means that mouse movement doesn't switch over to KB&M, while joystick movement doesn't switch over to controller.

The laziest and worst way they can fix this, is by adding a delay on how often control schemes can be switch. This would fix the exploitable parts, but absolutely gut accessibility harder than before.

Workarounds

There are no optimal workarounds for the accessibility issue that I've found, but here are three with their trade-offs (keep in mind reWASD is a partially premium software):

1. Rebinding analog stick to WASD inputs (native software / reWASD). Removes a lot of the benefit of using analog stick.
2. Rebinding mouse to right joystick (reWASD). This makes your mouse emulate the right joystick, but generally poorly emulates mouse movement ingame.
3. Rebind to only use mouse buttons. The mouse buttons in DBD seemingly don't always cause a control scheme switch, meaning they work somewhat consistently regardless of the current control scheme the game recognizes. (more testing needed, it seems the switching can eat any input)

All these options are less than ideal, but the rebinding to mouse buttons have worked OK for me on survivor.

Why I care (or why you might)

Obviously, the exploits these issues provide should not be in the game, and it is impossible to tell if someone is using hybrid control schemes specifically to exploit these. Bans for this would be at an impact to people who are using hybrid control schemes, for accessibility or otherwise.

Although it is not an issue for myself, I've come to be quite frustrated with BHVRs lack of action towards accessibility, especially since investigating this issue, although it's quite well known this extends to other accessibility issues throughout the game.

I myself have always been interesting in tweaking how I play games in creative ways, I discovered the stun immunity in the evening after creating this joke video about TF2 joystick air strafing mechanics. As mentioned in that video, I don't think we should be limited in innovating and adopting new control schemes that may suit us better. It is in some way strange that despite the culture around gaming nowadays we aren't curious to see what different types peripherals can change the way we play.

I have been adopting using a Azeron Cyborg 2 in some of the games I play, TF2 having very decent support for it with some interesting advantages. (good video by pinguefy on this aspect) A big portion of this interest is because I'm interested in and prefer not using 3 of my fingers just for horizontal movement. (WASD)

In DBD specifically, it is somewhat well known that there is a trade-off between KB&M and controller.

• Mouse movement allows you to have very good control over your camera, while KB&M limits you in movement direction. This means you have to use your camera to control the direction you move in, resulting in precise flicks when looking around to maintain your movement direction (where imprecision results in small losses in distance).
• Controller allows you to move in any analog direction, on the cost of having less camera control. Some pro players prefer or have otherwise switched to controller for this benefit.

Allowing hybrid control schemes in DBD would allow the player base who are currently compromising in these aspects to more freely express their skill. I don't think technical limitations should keep people back from playing the game how they prefer.