HLX/HL3 Bulletpoints - What We Know So Far

1. Development Timeline

A chronological log of every known public reference to HLX/HL3.

Date	Event
September 2020	Garry (Facepunch) gets access to Source 2. Accidentally commits to the s&box repo publicly on September 22nd, mentioning HLX in their portfolio — plausibly making 2020 the first year the project existed publicly.
October 9, 2020	An Artifact Foundry update (20:57:04 UTC) renames a reference to an Animgraph file in a model named `box_creature_model.vmdl` to `box_creature_model_hlx.vanmgrph`. This is the first public HLX reference.
2021	First developer builds of s&box are released to the public. Facepunch includes mentions of HLX in a lot of internal tools, including console helpers for HLX.
March 2021	First mention of an HLX soundevent file. We can safely say the project existed this year.
September 1, 2022	`CONCENTRATION_WARNING` soundevent mention added.
July 11, 2023	`build_break_master.png` created.
November 15, 2023	HL2 noclip documentation.
December 28, 2023	HL2 20th Anniversary update. Merges the base game and the episodes into one. Gabe Newell posts a cryptic tweet promising to release an updated Raising the Bar with more Episode 3 stuff next year, and uses his iconic G-Man voice in the video.
December 31, 2023	Valve actively talking about Episode 3 and promising to release updated Raising the Bar with more EP3 content next year.
December 6, 2024	HL2's ammo/weapon pickup sound added to core.
October 2025	`asset_science` icon asset tag added. Metadata shows it was made in October 2025. No further information known; could be unrelated to HLX or mean something else (like experimental assets).
March 19, 2026	CS2 update: Reserve ammo is now clips in CS2 with a new parameter being used.

2. Known NPCs Datamined

Information derived from datamined hint nodes and schema files.

Flitter

A flying enemy that circles around in a certain spot.
Has a landing spot.
Has holes/pipes that it uses as a Burrow Hole/Pipe.
This is similar to the naming for a similar system in HL2.

Xen Swooper

Circling Center — circles a central point.
Landing Spot — has a designated landing location.
Food — uses the same food that Antlions had in Half-Life 2.

Offworld Worker

Works at set locations, then returns to set locations.
Has hint nodes for picking up and dropping off physics props.
Unknown whether these are specifically for the Offworld or for the Combine more generally.

Offworld Stork

A flying creature that restocks (resources?) at a set location.
Deploys at a set location.

Pentatank

Some kind of tank with 5 legs (given the name).
Has set "sentry points" for turrets.
Could be a crab-like Combine tank, or a literal fuel tank protected by turrets.

3. Known Locations Datamined

Offworld

Appears to be a work camp where Combine and Citizens are sent if they misbehave.
Likely used to prepare resources for the Combine.
Overwatch line from Half-Life 2: "Citizen notice: Failure to cooperate will result in permanent off-world relocation."
"Offworld" could also just refer to any location that isn't Earth, including Xen, but there seems to be a clear distinction from Xen as a location in the hint nodes.

Foundry

A metal foundry with set spots for welding and communications.
Could be its own location, or could be within the Offworld (given that the Offworld might be a work camp).
The communications hint node could be for a strategic combat location — the player might have to invade the foundry or turn off its ability to communicate.
Only two hint nodes are known:
- HINT_FOUNDRY_COMMS — Foundry: Communications
- HINT_FOUNDRY_WELD — Foundry: Weld

4. Gameplay Mechanics Datamined

All mechanics below are derived from datamined Source 2 FGD (Forge Game Data) files and schema explorers. These are not speculation — they are present in the engine code.

4.1 Gravity Gun

Level designers can adjust objects in the scene with the following properties:

physcannon_maxforce / physcannon_minforce — Force greater than the max value on the physbox will enable motion. The Gravity Gun has a min and max force and can prioritize objects and shift whichever object is prioritized.
enableuseoutput(boolean) — "Enable +Use Output" — Enables OnPlayerUse output being fired when this object is used.
cannotgravitygrab(boolean) — "Cannot Gravity Grab" — Prevents the object from being grabbed.
cannotgravitypunt(boolean) — "Cannot Gravity Punt" — Prevents the object from being punted.
enablemotionongravitygrab(boolean) — "Enable Motion On Grab" — Enables motion when grabbed.
gravitygrabignoremassandsize(boolean) — "Grab Ignores Mass" — Grab is possible regardless of whether the object is too heavy or large.

4.2 Fire and Heat Conductivity

A comprehensive fire propagation system with the following surface attributes:

Attribute	Name	Description
`surfaceattribute.heatconductivity`	Heat Conductivity	How quickly this material absorbs heat from nearby heat sources, 0–1, where ≤0 makes it impossible to heat.
`surfaceattribute.flashpoint`	Flashpoint	How hot this material needs to be to light on fire, from 0–1, where <0 or >1 makes it not flammable.
`surfaceattribute.burnfuel`	Burn Fuel (seconds)	How long this surface could be ignited for before it runs out of fuel. Once spent it can't be reignited. 1 = infinite fuel.
`surfaceattribute.heataura`	Heat Aura (units)	How close something has to be to this surface to be heated by it.
`surfaceattribute.burndamage`	Burn Damage (Multiplier)	How much this surface modifies how much damage the fire on it gives.
`surfaceattribute.immediateignition`	Should Ignite Entities Immediately	Whether this should immediately ignite any entities that come into contact with it.
`surfaceattribute.flamestyle`	Flame Style	What sort of visuals should this fire use.
`surfaceattribute.firesound`	Burning Sound	What sound this makes when it's burning.

Additional Fire Interaction Data

Fire interactions gamedata node sets: MODIFIER VALUE TEMPERATURE, FLASHPOINT, MODIFIER VALUE HEAT DELAY, MODIFIER VALUE STARTS FIRES IN BOUNDING BOX (80%).
New fire-related surface attributes were added to core.
Surfaces can have their burn damage set and can immediately ignite objects that come into contact with them.
world.dev.flammable material exists.

4.3 Water / Liquids

While water is technically featured in CS2 and Dota 2, it does not function as you would expect. In those games, water is only a material shader and doesn't interact with phys props or the player.

Source 2 now supports previously unimplemented buoyancy seen in HL2:

The player can hold their breath and take drowning damage.
HoldBreath and DrowningDamage are in the CBasePlayerVData schema.
CTriggerBuoyancy entity exists with a CBuoyancyHelper component and m_flFluidDensity property.
CS2 lets you swim in it and makes you take underwater damage if you stay in too long. It doesn't seem to affect props inside the trigger.
For some reason, trigger_buoyancy is only compiled in CS2 and Aperture Desk Job.
The trigger's surface is converted to a water surface.
CS2 update 17.0925 — trigger_buoyancy is no longer exclusive to specific games.
New particle renderer: Water Ripple Impulse From Event.

4.4 Vehicles

A highly sophisticated, VData-driven, physics-based vehicle system is contained within base FGDs.

Construction

Vehicles are constructed using a vehicle_entityio entity.
Use VData subclasses to define their characteristics: subclass_name(subclass choice:scripts/vehicles.vdata) — "Vehicle Subclass" — Base class: BaseVehicle.
Vehicle passengers can have their subclass modified.

Passengers

Vehicles can contain passengers who can use their weapons while inside the vehicle.
Vehicle passengers have enter/exit animations (leads to the conclusion that anyone can enter a vehicle).
Output PassengerEntered(integer) — "Passenger entered the vehicle (argument is passenger index)."
Output PassengerExited(integer) — "Passenger exited the vehicle (argument is passenger index)."
The passenger index system implies multiple seats in a vehicle.
VehiclePassengerInteractionInfo and m_hPassengerPawn — the pawn subclass to create to control the vehicle (player passengers only).
Vehicle Entry/Exit Animgraph Finish Tags and Parameters exist for animating passengers getting in/out.
PASSENGER_ENTERING_VEHICLE animgraph parameter is set on the vehicle to animate the passenger getting in.

Driving & Physics

FOV changes depending on your speed (m_flFractionOfTopSpeedForHighSpeedFOV, m_flFractionOfTopSpeedForStandardFOV).
Wheels emit tire smoke with configurable intensity rise/decay time constants.
Tire friction — surfaceattribute.wheelfrictionscale — "Additional friction scale applied for wheels driving over this surface (on top of the physics friction coefficient)."
Wheel drag — surfaceattribute.wheeldrag — "Drag applied to vehicle wheels when driving over this surface."
Vehicle suspension system — Max/Min Suspension Offset, Enable Suspension Limit, m_flNonDrivableSurfaceFrictionScale, lateral/longitudinal collision scales.
Speed-based friction blending — Speed at which tire friction calculations are fully blended; speed at which blending starts between standard friction constraints and tire friction calculations.
Steering input — Has specific input for controllers. Steering rise/fall rates, steering range scale at high speeds, deadzone threshold for driving straight on a gamepad.
Vehicle flipping — Whether it's flipped on its side or upside-down.
Vehicles can potentially play procedural sounds.
Driving against an NPC with a vehicle hard enough can temporarily ragdoll them, even if they don't die.

Destructible Hit Groups

Vehicles have destructible hit groups. The following car parts can be destroyed:

HITGROUP_CHASSIS

HITGROUP_HOOD

HITGROUP_DOOR_FRONT_LEFT

HITGROUP_DOOR_FRONT_RIGHT

HITGROUP_DOOR_FRONT_LEFT_WINDOW

HITGROUP_DOOR_FRONT_RIGHT_WINDOW

HITGROUP_DOOR_MID_LEFT

HITGROUP_DOOR_MID_RIGHT

HITGROUP_DOOR_MID_LEFT_WINDOW

HITGROUP_DOOR_MID_RIGHT_WINDOW

HITGROUP_DOOR_REAR_LEFT

HITGROUP_DOOR_REAR_RIGHT

HITGROUP_DOOR_REAR_LEFT_WINDOW

HITGROUP_DOOR_REAR_RIGHT_WINDOW

HITGROUP_TRUNK

HITGROUP_HEADLIGHT_LEFT

HITGROUP_HEADLIGHT_RIGHT

HITGROUP_TAILLIGHT_LEFT

HITGROUP_TAILLIGHT_RIGHT

HITGROUP_WINDSHIELD

HITGROUP_WINDOW_REAR

HITGROUP_WHEEL_FRONT_LEFT

HITGROUP_WHEEL_FRONT_RIGHT

HITGROUP_WHEEL_REAR_LEFT

HITGROUP_WHEEL_REAR_RIGHT

4.5 Fans

Fans are a relatively new addition that we don't have too much information on.

They blow in a set direction.
Can pull towards a point.
Work with a specified amount of force.
Block players (and NPCs?).
Deadlock's fans do NOT currently make use of this entity. They use a trigger_catapult instead.
Particle types include PARTICLE_FAN_TYPE_1, PARTICLE_FAN_TYPE_2, and PARTICLE_FAN_TYPE_RADIAL.

5. Technical & Datamine Findings Datamined

5.1 Aperture Desk Job Files

Aperture Desk Job releases feature new versions of NPC/AI-related concepts. Note: These files (including new NPC abilities) are identical to their HL:A equivalents, while also featuring VData files that should not have been there (weapons, precipitation, squad definitions).

5.2 Sound Files

CONCENTRATION_WARNING soundevent mention added September 1, 2022.
HL2's ammo/weapon pickup sound added to core on December 6, 2024.
Sound files referenced: cy/eight.vsnd, legacy/four.vsnd.

5.3 Source 2 Schema Explorer

C_OP_RenderVolumetricEmitter — A class in particles.dll (Counter-Strike 2), extending CParticleFunctionRenderer with 12 fields including m_strChannelType.
Render volumetric smoke particle operator. Wants a smoke type from scripts/smokegrid.vdata. Data type for this file is not present.
New particle renderer: Water Ripple Impulse From Event.
New particle: Helicopters (similar effect seen).

5.4 Asset Tags

asset_science — An asset tag icon added in an update in October 2025. Metadata shows the icon was made in October 2025. No further information known; could be unrelated to HLX or mean something else (like experimental assets).

5.5 CS2 Updates

March 19, 2026 CS2 update: Reserve ammo is now clips in CS2 with a new parameter being used.
CS2 update 17.0925: trigger_buoyancy is no longer exclusive to specific games.
A method to query for names of valid internal loops at Valve was discovered. Some of the valid returns include "ALC", "HLX", and "HL3".

6. Announcement Rumors (2025) Rumors

Disclaimer from the board: This section is for plausible content, but within the context of rumours. It's important to keep in mind we don't have anything to back this up with, unlike the other sections which are backed up by datamines. Only more significant stuff will be mentioned here: be it the importance of a certain information or the person it's coming from in terms of the industry/past reporting. No, 197 does not count.

Mike Straw

Senior editor for Insider Gaming (also known as Tom Henderson's gaming news site).

Seems insistent on the idea there's another big Valve announcement and it's HLX.
"BTW, Valve isn't done with the big announcements. Soon enough there's going to be something else."
"It's happening soon enough. Just be ready."
Doesn't think it's likely to be at The Game Awards (TGAs), despite Valve being listed on the advisory board.
When asked if HLX will be on consoles: "I'm not sure. I'd assume so at some point whether launch or later, but with Valve you just never know."

Tom Henderson Debunked

Owner of Insider Gaming and just generally very notable insider on his own.

Initially rumored Half-Life 3, but has since debunked this himself.
Claimed he was not referring to Half-Life 3 and that his quote was misunderstood.
Claims to know nothing about Half-Life 3.
Source tweet

Jeff Grubb

Co-Owner of Giant Bomb, prominent insider also.

GiantBomb were officially at the press event for the Steam Hardware announcement.
In a podcast post-factum, Jeff (after asking his colleague if there was any indication of HLX) said he thinks it should be "around the corner."
Common theory discussed: HLX as a Steam Machine launch title, exclusive. Makes sense given the Steam Machine hardware.
Mentioned early 2026 / March 2026 as likely timeframe: "I've heard there's a big game coming out in March that I can't say just yet. But a lot of people are looking forward to it. We'll see in the next couple of weeks if we're gonna talk about it."
When asked about Half-Life 3: "They're still not talking about that if that's real. Uh, although I think it might still pop up here any minute."

Shaun Weber

Discussed the Steam Machine launch title theory.
Mentioned March 2026 as probable release window.

Tyler McVicker

Passionate Gamer.

Mentioned a rumor that a new trailer is in the works, with Valve planning to re-release Raising The Bar this year, possibly to coincide with a big Half-Life announcement.
Shared that a verified source working on the project said they had their "last meeting this year," which could mean an announcement is coming soon or that work might pause until after the holidays.
There have been several leaks from insiders hinting at a Half-Life reveal, though no one's confirming an exact date.
Tyler's been reaching out to these sources and feels positive about the whole ordeal, leading him to believe the game may be getting announced soon-ish.
Before November: The current rumor is that the trailer is being worked on. Valve has a coffee table book (Raising the Bar reprint with new Episode chapters) that they've announced as shipping this year. They're definitely going to want to sell that book at the same time everyone is freaking out about a new Half-Life game.
"I don't wanna put words into anybody's mouth or hype somebody for something that might not happen. Let's just tentatively get excited for November, let's mellow out about a possible thing happening soon, maybe."
During November: Somebody who is verified to be working on the project started telling people. Tyler was reaching out to people making public claims about Valve.
But he was unable to confirm the trailer rumors.

GabeFollower

Co-Founder of PassionateGamers LTD (joke).

"Valve is still aiming for a 2025 announcement."
Nothing has changed from information he received last year.
First mentioned a possible 2025 announcement in his first video on HLX, stating they were aiming for a "2024-2025" announcement.
- Source video
Also mentioned in his "Valve Playtests New HL3 - HLX news" video.
On 11/12/2025 at 8:50 pm: "according to my info from the last year, nothing changed, they're still aiming for 2025 announcement."
Clarification: "The info is from last year, and I haven't heard anything since then that would suggest it's no longer relevant. So, no, I don't have any new information, but I also haven't heard anything that would make me change my mind."
He was unable to confirm (or necessarily deny) Tyler McVicker's news of a Half-Life 3 trailer rumored being in production, with his source(s).
"Never even commented on recent rumors and failed to get any confirmation about a possible trailer being in the works, and also any confirmation about the coming weeks. It's still just 2025, no idea where all the rumors about this week came from."

Jason Schreier

Gaming journalist well known for reliable industry leaks.

"Half-Life will make a return."
"There's been a lot of smoke surrounding the resurgence of Valve Corp.'s iconic shooter series."
"I would love to do [more Half-Life]" — not in the decision-making process.

General Insider Activity

Bunch of insiders in the industry started talking about something happening soon, possible announcement. Mostly November.

7. Valve Interviews (March 2020) Interview

Snippets from interviews with Valve conducted around the release of Half-Life: Alyx (March 23, 2020).

Robin Walker (Valve Employee)

On VR vs. non-VR for future Half-Life:

"At this point, we don't really know what [another Half-Life game] would be — we don't know if it's going to be another VR title. We don't know if it's going to be a non-VR title. The best thing we can do at this point is to gauge the response to this product. How are people able to enjoy it? How many people can we get into the VR platform? [Are] people saying that VR is now this essential part of Half-Life? We really don't know those answers until we put the game out and we start listening."

On continuing the series:

"With Valve it tends to be more of a human problem than a business problem, but I do think it's clear that a lot of people had a hell of a lot of fun making this game and we're really proud of it. That's pretty important to the likelihood that we continue to work on this sort of stuff. There's a lot of eagerness to continue working on it."

On the team's desire to continue:

"It's sort of a truism in game development that it's at the end of the game when you've finally got good at making it. You're like, 'man, if we made the game again now it'd be really good!' So that's playing out in the team right now as it always has and I think we'd really enjoy to get to continue and build whatever the next piece of Half-Life is and see whether we get to do that."

Articles Published March 23, 2020

Publication	Headline
PCGamer	"The response to Alyx will determine the role of VR in Half-Life's future, Valve says"
VGC	"Interview: Valve on Half-Life after Alyx"
Kotaku	"Why Valve Gave Up On 'Multiple' Half-Life 3s"
Polygon	"Don't expect another 13 years between Half-Life games, Valve says"
USG	"Half-Life: Alyx Behind the Scenes Part 1: How Valve Found Its New Alyx"

Key Quotes

Kotaku: "We really enjoyed making this game, and I think we'd really like to keep making some games like this again." — Robin Walker

Polygon: "Don't expect another 13 years between Half-Life games, Valve says."

Summary

This board documents all known evidence for Half-Life X / Half-Life 3 — Valve's unannounced next Half-Life game, in active development on Source 2.

The datamined evidence (NPCs, fire propagation, vehicles, water physics, locations) strongly suggests a new Source 2 Half-Life game is in active development with significant new gameplay systems:

A fire and heat conductivity system with material flashpoints, burn fuel, and heat auras — far beyond anything in previous Source games.
A fully physics-based vehicle system with destructible hit groups, multiple passengers, tire friction, and suspension.
Water with buoyancy and drowning — previously unimplemented in Source 2, now restored from HL2.
New NPCs including the Flitter, Xen Swooper, Offworld Worker, Offworld Stork, and Pentatank.
New locations including the Offworld (a Combine work camp) and the Foundry (a metal foundry with communications and welding points).
An upgraded Gravity Gun with per-object grab/punt control and mass-ignoring.

The rumor section indicates insiders expected a 2025 announcement that did not materialize. Some insiders now point to early 2026 (possibly March 2026), potentially as a Steam Machine launch title. GabeFollower maintains Valve is still aiming for a 2025 announcement. Tyler McVicker reported a trailer is in the works but could not confirm it. Tom Henderson debunked his own HL3 rumor.

Valve's own statements from 2020 express eagerness to continue the series and suggest the gap between Half-Life games won't be as long as the previous 13-year gap.