Update – April 20, 2023

Today, Alien Swarm: Reactive Drop celebrates 6 years on Steam. You’ll earn double experience points all week, but we know what you’re really here for. Let’s unwrap some presents:

New Campaign: Accident 32

Mysterious green glowing gems are discovered under the ground of a populated area due to abnormal radioactivity levels. The company “AMBER” comes to study this supernatural material. Findings are frightening and undocumented, and kept away from the public. The gems are identified to be extremely dangerous, extraterrestrial materials comprised of mostly muons. Emitted radiation modifies all biological structures in a big vicinity.

Originally released in May of 2020 and May of 2022 on the Steam Workshop, Accident 32 is a six-mission campaign which combines two three-mission campaigns into one. Marines are set out to explore the mysterious complex and headquarters of the company called “AMBER” and face many threats. A bonus “AMBER Complex” mission is included which is the first three missions combined into one.

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Collections: Weapons, Equipment, and Swarmopedia

As promised when the Collections screen was added, the Swarmopedia has returned, better than ever! Unlock stats, tips, and short stories about aliens by killing them in the field. Add-ons can also create their own Swarmopedia entries or add content to existing ones.

The new Swarmopedia entries (and this sentence) were written by the Internet’s beloved Grace Lovelace!

With the Swarmopedia revamp comes a new screen for selecting weapons using a grid intended to speed up finding high-level weapons and help with muscle memory. Unlocking weapons by leveling up now also gives you access to their fact sheets, with precise statistics about range, damage, and more.

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Mapping Competition 2023: “Boss Fight”

This year, we’re hosting our first annual community mapping competition, and what better place to start than at the end? The theme for this year is Boss Fight.

Create a mission or short campaign that contains a boss fight – a scripted encounter with some big bad that the marines must overcome. Will the boss be an alien, a group of aliens, or something completely new? Where will the mission take place? Why are the marines there? All of these questions and more are things you’ll have to consider in the coming months.

Or, if you have a better idea, go ahead and make that instead! AS:RD mapping competition themes are optional.

Entries must be tagged with BossFight2023. Competition starts today and ends August 1st. Prizes include unique ingame medals. If you need help getting started, check out the Modding / Mapping Help and Tips forum.

Year in Review

In 2022, marines killed 985,092,535 aliens in official missions and an additional 56,154,088 aliens in missions from the Steam Workshop. 575,108 players tried Alien Swarm: Reactive Drop for the first time last year. Including returning players, marines spent 1,590,427 hours in 17,674,520 missions. 10,947 players took part in at least one of the first six seasons of Heroes of the Interstellar Armed Forces by playing on participating community dedicated servers. December 6th saw the highest player count of the year, with 16,080 players logging in – over three times the average. Alien Swarm: Reactive Drop was played from 85 different countries in 2022.

Killing that many aliens takes a lot of ammunition – you fired 5,303,484,897 bullets last year – that’s about half as many bullets as are manufactured in the entire world each year – and that doesn’t even count weapons that don’t fire bullets. Marines also fired 232,409,109 shotgun shells, deployed 11,307,827 mines, and used 104,722,710 grenades. You launched 274,157,391 missiles and fired flamethrowers for a total of 86 million seconds, not to mention using chainsaws for over 1.4 billion seconds. (That’s over 45 years!)

It wasn’t just handheld guns and explosives, either. Last year, marines deployed:

  • 905,280 doses of Adrenaline
  • 3,890,668 ammo stashes
  • 1,501,644 X-33 Damage Amplifiers
  • 10,282,887 IAF Heal Beacons
  • 3,783,431 IAF Advanced Sentry Guns
  • 523,062 IAF Incendiary Sentry Guns
  • 261,255 IAF Freeze Sentry Guns
  • 260,971 IAF High Velocity Sentry Cannons
  • 3,822,448 IAF Tesla Sentry Coils

Marines also brought 105,866 flashlights along on missions.

You’ve destroyed 2,147,368 pieces of Biomass in 2022 since we started tracking it in late August. Between when we started tracking alien deaths in mid-June and the end of 2022, marines have killed:

  • 582,811,354 Drones
  • 28,956,762 Parasites
  • 27,244,232 Xenomites
  • 16,772,012 Rangers
  • 15,897,059 Eggs
  • 14,968,328 Buzzers
  • 11,929,443 Grubs
  • 2,940,237 Harvesters
  • 2,863,582 Boomers
  • 2,190,344 Menders
  • 1,945,290 Shieldbugs
  • 1,851,113 Mortarbugs
  • 577,023 Antlions
  • 186,411 Headcrab Zombies
  • 3,489 Queens

In Case You Missed It

Here are some highlights from updates since the previous anniversary:

  • Workshop addons can now contain videos, and missions can define their own briefing background video, or even show part of the world as the background during briefing.
  • We’re Steam Deck verified! The game runs great on the Steam Deck, and players on Linux or who use a controller have also seen improvements.
  • There are now medals you can earn by helping with the game’s development, contributing to the Steam community hub, or participating in a season of Heroes of the Interstellar Armed Forces.
  • The slow-opening vault doors used in many missions now have more accurate collision data, allowing you to step or shoot through a partially-opened door.
  • The all-new mission selection screen includes support for bonus missions and new “endless” missions.
  • We’ve added an advanced settings menu and an advanced audio settings menu.
  • Restarting a mission no longer requires a loading screen.

Other changes in this update


  • Area 9800: Wastelands: Fixed a harvester getting stuck in the exit during the finale gauntlet introduction scene.
  • Tears for Tarnor: Oasis Colony Spaceport: Fixed train station announcements being too quiet to hear in some cases.
  • Tears for Tarnor: Oasis Colony Spaceport: Reduced networking overhead in areas where the path through the mission crosses.
  • Tilarus-5: Arctic Infiltration: Fixed uber drones appearing and disappearing shortly after the start of the mission.
  • Tilarus-5: SynTek Hospital: Made alarm sounds louder. Dramatically reduced networking overhead.
  • Lana’s Escape: Lana’s Bridge: Significant performance optimizations to lighting, rendering, and pathfinding.
  • Lana’s Escape: Lana’s Sewer: The radioactive barrels in the arena deal more damage to menders.
  • Paranoia: Unexpected Encounter: Fixed bugs related to grenade launcher aiming.
  • Paranoia: Hostile Places: Fixed bugs related to grenade launcher aiming.
  • Nam Humanum: Logistics Area: Increased speed run time limit from 1:10 to 1:15.
  • Nam Humanum: Platform XVII: Increased speed run time limit from 3:02 to 3:10.
  • Nam Humanum: Platform XVII: Fixed bot marines refusing to stand on the moving platform.
  • BioGen Corporation: Operation X5: Increased speed run time limit from 3:28 to 3:35.
  • BioGen Corporation: Invisible Threat: Increased speed run time limit from 1:13 to 1:20.
  • Bunker: Removed collision from an invisible ceiling beam.
  • Landing Bay + Cargo Elevator: Fixed a soft lock caused by completing the objectives out of the intended order.
  • Added an official bonus mission based on Accident 32.
  • Added four new official bonus missions based on Jacob’s Rest.
  • IAF Marine Academy: Added a new official Endless mission.
  • All official missions have been given custom loading screens.


  • ML30 Laser Trip Mine: Improved network prediction for throwing animation.
  • L3A Tactical Heavy Armor: This equipment now changes the appearance of marines wearing it.
  • Hornet Barrage: This equipment now changes the appearance of marines wearing it.
  • CR-18 Freeze Grenades: Freezing now kills buzzers, and marines can be frozen in Deathmatch mode.
  • K80 Personal Defense Weapon: This weapon now shows a different icon for magazines on the HUD instead of counting each magazine twice.
  • M868 Flamer Unit: Fixed fuel tanks only granting half a reload worth of ammo.
  • v45 Electric Charged Armor: This equipment now changes the appearance of marines wearing it.
  • Flashlight Attachment: This equipment now changes the appearance of marines wearing it.
  • IAF Power Fist Attachment: This equipment now changes the appearance of marines wearing it.
  • Chainsaw: Bots now use this weapon from a more reasonable range.
  • MTD6 Smart Bomb: This equipment now changes the appearance of marines wearing it.
  • MNV34 Nightvision Goggles: This equipment now changes the appearance of marines wearing it.
  • IAF Medical Amplifier Gun: Primary fire now self-targets when aiming with the right stick or holding the crouch key (shift), or when in first or third person, if the target being aimed at is not valid for healing.
  • TG-05 Gas Grenades: Updated the item’s appearance to help differentiate it from other types of grenades.
  • IAF Medical SMG: Secondary fire now self-targets when aiming with the right stick or holding the crouch key (shift), or when in first or third person, if the target being aimed at is not valid for healing.
  • Flechette Gun (hidden): This gun has a new appearance and now fires timed sticky explosives (the same ones Combine Hunters fire) rather than auto-aimed rockets. Now fires directly at the aim location rather than parallel to the ground.
  • Ricochet Rifle (hidden): This gun has a new appearance and no longer requires the secondary trigger to be held to bounce shots. Instead, holding the secondary trigger switches the gun to a shotgun-like burst fire mode. Bounced bullets can now hit the marine that fired them.
  • Displacement ‘Blink’ Pack (hidden): This equipment now changes the appearance of marines wearing it.
  • Short Range Assault Jets (hidden): This equipment now changes the appearance of marines wearing it.
  • Fixed the scanning animation for sentries desynchronizing from the gun’s idle angle.
  • Fixed inconsistencies in collision-checking code, most notably related to bot marines and projectiles.
  • Auto-aim weapons such as the 22A7-Z Prototype Assault Rifle and the S23A SynTek Autogun now apply their bonuses in first and third person.


  • Fixed an issue where server-triggered achievements such as speed runs and Outstanding Execution could be skipped due to momentary packet loss.
  • Fixed a crash when an alien tried to throw a physics object at a target who had died.
  • Fixed a crash when leaving a screen with a dropdown menu open.
  • Fixed the game instructor recommending marines to weld a door that is already damaged to the point where it cannot open or close.
  • Fixed marines being unselected in the lobby when restarting a bonus mission that was started via a vote.
  • The chat panel can now be opened in singleplayer (for use in custom challenges).
  • Improved bots in Deathmatch maps. They should get stuck less, turn at more reasonable times, and will now automatically join if you start a Deathmatch map in singleplayer.
  • Fixed the game instructor giving incorrect information about how to respawn in Deathmatch mode, and tidied up the prompts on the HUD.
  • Improved bots’ ability to avoid danger and flank shieldbugs.
  • Bots are now much less likely to teleport in front of a player.
  • You can flush the toilets in official missions.
  • Marines no longer always face east when starting a mission in first or third person.
  • Fixed some tooltips being too small to comfortably read.
  • When selecting a text input with Steam Big Picture enabled, the on-screen keyboard will open.
  • Added a mission recording list and an option to automatically record missions.
  • The game now updates its state more frequently during slow motion.
  • Performing an override on a locked computer now always goes to the menu rather than downloading critical data or doing nothing.
  • When finishing a bonus or deathmatch map, the game now selects a default next mission.
  • The Leadership skill can now be triggered by any officer within range, not just the officer with the most points in the skill.
  • Added a visible and audible indication for when Leadership affects damage dealt or taken.
  • Challenges can now set “required_on_client” “1” if they wish to include assets, which will cause the workshop addon to be automatically downloaded when the challenge is activated.
  • Challenges can now be marked for use in deathmatch with “allowed_mode” “deathmatch”. Challenges that are able to be used in both deathmatch and cooperative play can additionally specify “allowed_mode” “coop”.
  • Fixed several Nam Humanum campaign achievements re-locking unexpectedly.
  • Fixed the Perfect achievement requiring no challenges in the current lobby rather than the current mission attempt.
  • Updated the weapon unlock notification to include a description. This screen is now also used for medals unlocked through gameplay.
  • Added advanced settings to highlight your character, play sounds when you hurt an enemy, and more!


  • Added npc_crow, npc_pigeon, and npc_seagull.
  • Added npc_combine_s, npc_combine_shotgun, and npc_combine_elite. These soldiers lack the “swarm sense” of aliens, instead relying on sight, sound, and information from their squad. Mappers can optionally add info_node_hint to mark spots with cover for the Combine soldiers to use.
  • Added npc_zombine, with mapper-configurable grenades.
  • Added npc_hunter, for use with other Combine NPCs.
  • Added npc_strider, npc_combinegunship, and npc_combinedropship for use in cinematics.
  • asw_colonist is now randomized using a wider range of appearances. Set the skin number to change the color of their clothing.
  • asw_env_shake can now be flagged to bypass user settings (a new convar has been added for disabling all shakes regardless of this flag).
  • Added env_headcrabcanister.
  • Added script_intro.
  • A new material proxy, LanguagePreference, can be used to change a texture based on the viewer’s language preference. For example:
    UnlitGeneric {
        $basetexture "example/translated_texture_english"
        Proxies {
            LanguagePreference {
                default "example/translated_texture_english"
                schinese "example/translated_texture_schinese"
                french "example/translated_texture_french"
                resultvar "$basetexture"

  • TileGen now expects rooms to be built for -alldetail mode (world brushes turn into func_detail, func_brush with a name starting with structure_ turns into a world brush).
  • Improved the randomization of rd_tilegen_instance.
  • rd_tilegen_instance now searches in reactivedrop/tilegen/instances rather than reactivedrop/tilegen/instance/ThemeName.
  • TileGen now flattens instances before sending the map to VBSP, allowing TileGen room sets to be distributed in VPKs or on the workshop. This also means rd_tilegen_instance can be used within instances.
  • TileGen maps now use toolsskybox for a level seal, allowing the use of light_environment and light_directional.
  • asw_vehicle_jeep is now functional. Available vehicles without add-ons are the dune buggy from Half-Life 2 (models/buggy.mdl, scripts/vehicles/jeep_test.txt) which allows one driver, and the muscle car from Half-Life 2: Episode Two (models/vehicle.mdl, scripts/vehicles/jalopy.txt) which allows one driver and one passenger.
  • trigger_asw_button_area now has options for overriding UI hints with custom text.
  • trigger_asw_computer_area has been made more customizable:
  • Mail and news articles can now optionally end with an image. Use Image, ImageWide, and ImageTall to add an image to a news file. For mail, use MailBody1Image, etc.
  • Reactor status can be controlled via an input on the computer area, as an alternative to the old method of having an objective with a specific icon.
  • Weather, reactor status, and stock market info can now be customized with keyvalues files. Additionally, the current temperature is no longer randomized every time the weather report is opened.
  • The buildcubemaps command now requires sv_cheats to be enabled.
  • func_asw_fade now ignores collisions with grenades by default.
  • Added asw_weapon_ar2 and asw_ammo_ar2. The Pulse Rifle can only refill ammo from these specific ammo packs and cannot use generic ammo stashes.
  • Added asw_ammo_grenade_launcher, asw_ammo_sniper_rifle, and asw_ammo_heavy_rifle.
  • Added info_marine_hint_dynamic, which can be assigned a parent and moved.
  • Added rd_hud_counter, which can be used to display an dynamic arbitrary number to all players or to one specific player.


  • Added a new method to marines: SetMarineRolls, which allows maps and challenges to change whether individual marines can jump.
  • Added a new method to marines: SetNightVision, which can be used to enable night vision mode on a marine regardless of whether they have MNV34 Nightvision Goggles.
  • Added methods to marines: IsInfested and IsElectrifiedArmorActive.
  • Added methods to marines: OrderHackArea, OrderUseItem, OrderFollowSquadLeader, OrderHoldPosition, and OrderMoveTo.
  • Fixed GetClips, GetMaxClips, and SetClips on weapons to work properly when the weapon is dropped. It will also return -1 for weapons that can’t be reloaded.
  • Inhabitable NPCs (such as marines) have a new method: SetControls, which overrides the value of asw_controls for anyone playing or spectating that character. Negative numbers cause the character to use the global setting.
  • Added a new method to Inhabitable NPCs: SetGlow, which can be used to add glowing outlines to aliens and marines. This does not affect characters that would normally glow without a call to this function.
  • asw_vehicle_jeep has methods to override its camera, SetCameraControls, SetCameraPitch, SetCameraDist, and SetCameraHeight, with corresponding Get* methods. Setting a negative value causes the vehicle to use the global setting.
  • asw_vehicle_jeep has methods to query the occupants: MaxPassengers(), GetDriver(), and GetPassenger(seat).
  • asw_vehicle_jeep has methods to retrieve statistics: GetSpeed, GetMaxSpeed (in miles per hour), GetRPM, GetThrottle, HasBoost, and BoostTimeLeft.
  • Added SetSpawnZombineOnMarineKill to inhabitable NPCs, SetSpawnZombineOnDeath to marines, and a convar rd_marine_spawn_zombine_on_death_chance, all of which can be used to spawn a marine zombie with the Zombine AI when a marine dies.
  • Added methods to players: SetNPC and SetSpectatingNPC.