SI 1.4b2 released!

SI 1.4b2 has been released! Click here to download the installer.

(Or click here if the installer gives you trouble)

Here is the list of changes:

  • EMP Cannon secondary attack is the canister again
    • Lightning gun removed
  • Ocular Implants show markers for a bit more time after vision is lost

SI 1.4b1 released!

SI 1.4 has been released! Click here to download the installer.

(Or click here if the installer gives you trouble)

Here is the list of changes:

  • Redesigned Ocular Implants

    • Tier 3 implant: can be researched after exoskeleton, superjump, legs2 or ammo2 is complete
    • Reveals objects your teammates can see that are hidden from your view
    • Does not reveal cloaked enemies
    • Does reveal cloaked teammates
    • Research time is 1 minute
  • Restored the old Satchel firing speed (1 bomb / second)

  • New EMP Cannon secondary attack: Lightning gun!

    • Uses ammo at the same rate as primary fire
    • Each hit does 12 the damage of a primary fire pulse
    • Fires 13 times per second (same as tommygun)
    • Range is limited
    • Shocks a small area around where it hits (useful to destroy radios)
    • Shoot a flying EMP pulse to detonate it, discharging all ammo
  • New Teleport Kit models

  • New GI Destabilizer wave graphics

  • Rocket Pistol damage lowered to 110

  • Tau Cannon changes

    • Research time reduced to 2.5 minutes (from 3.25)
    • AOE nuke damage returned. Radius and damage are half of the main shot damage. Nukes happen on every wall pierced.
    • Charge time reduced from 1.7 seconds to 1.3 seconds
  • Updated the minimap sprites for resources, breakables, administrator, and dead players

  • Map update: si_crucible now a bit easier to defend thanks to new routes

  • Globally reduced knockback from damage by 40%

  • Dead players no longer drop items

    • Set the svar dropitems to 1 to restore the old behaviour
  • Added new commands to select weapons and devices more easily

    • weapon1 selects the pistol or briefcase (press again to cycle through items)
    • weapon2 selects shotgun or tommygun
    • weapon3 selects nailgun, hand grenades or FEV
    • weapon4 selects tau cannon, crossbow or rocket pistol
    • device1 selects cloak or radios
    • device2 selects mindray, EMP cannon or GI destabilizer
    • device3 selects tripmines, satchels or the teleport kit
    • This allows you to select all the weapons with a fixed set of 7 key binds
    • The only time you need to ‘double tap’ a key (to cycle items) is when you have multiple techs in the same group (e.g. tau and crossbow, mindray and EMP)
    • Other methods of selecting items are still available as before
  • Removed third person view (briefcase and cloak)

  • Updated the main menu

  • Updated the default config with better mouse, network and graphics settings

SI 1.3b8 released!

SI 1.3b8 has been released! Click here to download it.

Here is the list of changes:

  • Fixed Nailgun bleeding on players

  • Fixed Tau Cannon bugs

    • Kickback going in the wrong direction sometimes
    • Shots hitting the firing player sometimes
  • Added svars quadtime and quadrespawn to adjust quad damage resources

    • quadtime sets how long a picked-up quad lasts (default 20)
    • quadrespawn sets how long it takes a picked-up quad to respawn (default 60)
  • The teampanel will show teammates who have quad damage with an orange background

  • Kill notices from quad damage have an orange kill icon

  • Friendly fire kill notices show the weapon used

  • Restrict pitch and yaw adjustments (prevents rocketjump/taujump scripting)

  • Added the svar explosion_dropoff to change how explosions deal damage

    • Set this to 1 to make explosions smaller, but more damaging up close
    • Set this to 0 to have explosions behave as they used to
  • Removed a source of randomness in explosion damage

  • Added the hud_damageindicator cvar. Set this to 1 to disable the damage indicator sprite (or 0 to keep it on).

SI 1.3b7 Released!

SI 1.3b7 has been released. Click here to download it.

Here is the huge list of changes:

  • Map updates:

    • si_crucible: A new map full of Quake nostalgia, ideal for small teams.
    • si_late: Lots of revisions!
    • si_hrim: Lowered the middle of the mid-map, the elevators are now toggled by the buttons
    • si_mill: Lots of revisions! Scientists now only spawn on the bottom floor
    • si_vestibule: Lots of revisions! Trim on doorways, opened up the main lobby entrance
    • si_mesa: Added a map overview image and location markers
  • Added the Nailgun

    • Alternative to Grenades and FEV (tier 2 weapon)
    • Primary fire shoots nails that bounce with no friction (wide-angle reflections)
    • Secondary fire shoots nails that bounce with high friction, high gravity (tight-angle reflections)
    • Nails deal 80 damage
    • Fires 3 shots per second
    • Holds 5 shots, reloads in 1.5 seconds
    • Ideal for clearing out vents and tight hallways. Not so good in open areas.
    • Lots of svars to control these in testing:
      • ng_time: How long nails fly for before disintegrating (default is 0.8)
      • ng_grav: Gravity on secondary fire nails (default is 0.8)
      • ng_fric: Friction on secondary fire nails (default is 0.8)
      • ng_tt: How long the smoke trail draws for (default is 1)
      • ng_s: Size of nails, length of one side of the cube (s x s x s, default is 4)
  • Added Quad Damage

    • Replaces resources (when the svar quadresources is set to 1)
    • Lasts 20 seconds
    • Respawns in 1 minute. Does not spawn at game start.
    • All damage dealt by the player is multiplied by 4 while active
    • Official maps with resources: deep, daybreak, green, mercato, turf, overtime, spa…
    • A strategic powerup that lets one player stand out, clearing a path for their team
  • Tau Cannon changes:

    • No longer deals splash damage when hitting walls
    • Pierces walls, people and other objects over a large distance (set by the svar tau_distance, default is 8192)
    • Fixed fake shots when holstering the gun while charging
  • Mindray changes:

    • Simplified the sounds and visuals to be more reliable
    • Primary fire shoots 10 times per second, uses ammo quickly, has very long range and raises efficiency quickly
    • Secondary fire is unchanged
  • Crossbow damage raised from 120 to 125 (this actually matters)

  • Satchels are now thrown every 2 seconds (slowed from every 1 second)

  • Reduced the splash radius of rockets, grenades, satchels, teleport grenades

  • Reduced knockback from weapons globally (controlled by the svar dmg_kb, default is 4)

  • Added m_raw to control mouse settings.

    • Set this to 1 to get the same effect as the launch option -noforcemparms (no acceleration etc).
    • Set this to 0 and your mouse settings are unchanged.
    • If you had trouble recently with launch options or needed to run the rinput.exe tool, this should be just as effective (with less input lag and less moving parts).
  • The vote menu can be opened at any time. Your vote can be re-cast before the next tech starts researching.

  • Dead players are always indicated on the scoreboard (in all game modes)

  • Overview map now also shows resources, breakables and friendly living scientists

  • Health kits now add 50% of your maximum health when picked up

  • Armor kits now add 50% of your maximum armor when picked up

  • EMP bolts and grenades are now team-coloured

  • Improved consistency of wall jumping

  • Fixed zoom being stuck on while dead or spectating

  • Made radios and tripmines a bit easier to shoot

  • cl_autorecord now starts a new demo upon startmatch

    • No more searching in long demos for the game start time

1.3b6 Released!

SI 1.3b6 has been released. Here is the list of changes:

  • Map updates:

    • si_late: Lots of revisions!
    • si_hrim: A few small changes!
    • si_mill: Lots of revisions!
    • si_vestibule: A work-in-progress revision of si_alley
  • Research time changes:

    • Health regen 1 minute
    • Armor regen 1 minute
    • Tissue recycling 2 minutes
  • Scientist knockout and throw changes:

    • You can only knock out 1 scientist every 10 seconds
    • You can pick up and throw scientists (+attack2 with the briefcase) as often as you want
  • Zoom changes:

    • default_fov sets your regular FOV angle (e.g. 90 degrees)
    • zoom_fov sets your zoom FOV angle (e.g. 70 degrees)
    • Zooming is purely clientside
  • Crossbow refire time reduced to 0.75 seconds

    • Tracer effect removed
  • Many improvements to weapon switching delays

  • +use no longer slows down the player when pressed

  • FEV Secondary fire poison lasts 6 seconds (same as the adrenaline effect)

  • EMP can destroy teleport grenades. Teleport grenades cannot be killed otherwise.

  • Scientists thrown to the Administrator are captured automatically

  • Dead Scientists now use the player spawn times (4/3/2 seconds depending on Process tech)

  • Rocket Pistol barrel smoke effect removed

  • Fixed +attack being stuck on by the scoreboard

  • Added hud_saytext_volume to adjust the chat beep sound (1.0 is default, set to 0 for blissful silence)

  • Fixed lots of issues with the spectator view being broken

1.3b5 Changelog

  • Map updates:

    • si_bavaria: Made labs a bit easier to defend, improved the conveyer belts, lots of improvements to FPS
    • si_hrim: A very good new map by grome!
    • si_late: A different take on si_early, with changes to make gameplay faster and more interesting
  • Radios are brighter

  • EMP has a kill icon

  • LCS: dead players are shown with colorized names, instead of dead

  • Healthkits give 25 hp and Armor Batteries 25 armor

  • Mindray no longer reveals enemy research

  • Revised weapon switching:

    • If you hold +attack or +attack2 while selecting a weapon, you must release it before you can fire again
  • Fixed Superjump “head sliding”

  • Fixed Tau Cannon ‘wall bleeding’ on nukes

  • Tau Cannon can no longer shoot the sky

  • Disabled Ocular Implants.

  • Zoom is available by default, and there are no ranged damage upgrades.

  • Removed the saytext sound.

  • GI Destabilizer secondary fire pushes from lower

  • GI Destabilizer has instant deployment

  • Removed cl_effects_fev_cloud_density

  • Made consistency checking more strict: always checks all player and projectile models

  • Reduced FEV adrenaline time to 6 seconds

  • New cvars for weapon switching:

    • cl_altweapon_backup: set to 1 so you can equip an alt weapon without pushing +altweapon
    • cl_altweapon_cycling: set to 1 to enable cycling between a weapon and its alt without pushing +altweapon

Steam Group

Click here to visit the SI Steam Group.

Feel free to post on the forum about how much you love the game, or find out when the next pickup game will be played!

In the pickup games, we use Mumble for voice communication.


Click here to download the SI installer.

Or try here if the installer gives you trouble.

SI is a Half-Life mod. You need Half-Life installed to play it.

Extract the archive to your Half-Life directory in Steam.

When the mod is installed, your folder structure should look like this:

├── htmlcache
├── platform
├── si
├── valve
├── valve_hd


Here are some links to cool streams and videos of SI: