The X-ray engine uses GSC Gameworld's proprietary ALife artificial intelligence engine. ALife supports more than one thousand characters inhabiting the Zone. These characters are non-scripted, meaning that AI life can be developed even when not in contact with the player.

The NPCs have a full life cycle (task accomplishment, combat, rest, feeding and sleep) and the same applies to the many monsters living in the Zone (hunting, attacking Stalkers and other monsters, resting, eating, sleeping). These monsters will migrate in large groups. The non-scripted nature of the characters means that there are an unlimited number of random quests. For instance, rescuing Stalkers from danger, destroying Stalker renegades, protecting or attacking Stalker camps or searching for treasure. The AI characters travel around the entire zone as they see fit.

Numerous tactics can be employed to complete the game, such as rushing or using stealth and sniping. The NPCs will react in a different way to each of them. S.T.A.L.K.E.R.'s NPCs plan ahead by "Goal-Oriented Action Planning" in order to achieve this.

Bullet physics

S.T.A.L.K.E.R. uses "realistic" bullet physics, similar in nature to tactical shooters such as Ghost Recon Advanced Warfighter or Operation Flashpoint. Bullets are affected by gravity, bounced against solid surfaces at oblique angles, and firearms are highly inaccurate when fired without aiming. To score consistent hits at medium or long range, players must aim using the iron sights
on their guns. Additionally, hit damage is pseudo-realistic, and the player can die after only being shot a few times (although later in the game various armor suits and artifacts can be acquired that increase the player's resistance to damage). Late-game depends heavily on scoped weaponry due to the well-armed and powerful enemies that keep their distance from the player.


S.T.A.L.K.E.R. uses a heavily modified version of the ODE physics engine, supporting hundreds of physics objects on different levels. Ragdoll physics, destructible objects, realistic bullet ballistics and skeletal animation can all be found in the game.


A weather system is integrated into various parts of the landscape and allows a variety of weather effects, such as sunshine, storms and showers. The weapons available, behavior of the AI, game tactics and ranking systems will depend on the weather.

For more direct specifications, check the engine's homepage.

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Time has built up between the last update I shared about this project, many things have changed and many things will keep up changing.

I have been making changes on the software, and it is now fully open for new possibilities. Although this tool was initially designed for S.T.A.L.K.E.R., I made recent changes in its core libraries to make it both attractive and flexible. What does this mean? Well, let me show you:

- New GUI

S.T.A.L.K.E.R. Optimizer brand new GUI

The Optimizer will feature a brand new GUI, far more attractive than the previous interface. Each item will have its info box to let the user know what does each button do, things will be kept in the simplest way possible both to provide a harass-free experience and to keep the resources consumption to the minimum, while providing rich features and good-looking forms.

- Added flexibility

Optimizer console

While the main purpose of this tool was reducing the chances to get memory leaks and related CTDs with X-Ray Engine (S.T.A.L.K.E.R. games), I had another idea... a console to make this tool work for any process. With this full-flexible console, the tool will work for any process with three defined actions: DIRECT OPTIMIZATION, MONITORING, and TERMINATING. These integrated functions will allow the tool to optimize a process once, monitor a process and optimize it each interval of time, or force the termination of a process. BUT, as you may have noticed, this flexibility brings downsides. Many malicious users might use this tool to cause memory related malware like worms, or CPU hogging malware, and that is why I intend to keep the tool hard-coded.

What I mean is, while the tool will be able to assist ANY game in memory duties, I will NOT let the user access directly to the console to avoid issues. So if you want your favorite game in the next version's (not 1.0, but 2.0) list then just leave a comment with the name of the game or PM me about it and I will add it.

That said, I will include that from the next version (not 1.0, but 2.0) and on, the tool will be called "Memo Creeper" and will be fully flexible to support any process without issues.

List of new features -> S.T.A.L.K.E.R. Optimizer 1.0:

- Brand new interface.

- Internal code fully optimized

- Console based tasks for optimizing, monitoring or terminating processes

- Full integration with S.T.A.L.K.E.R. Engine (X-Ray) (via scripting)

Coming features -> Memo Creeper 2.0:

- Multi-purpose optimizer, with support for variety of games/engines

- Memory leaks recognition for internally listed games

- Automatic detection and termination of hanged games

- MAYBE a restricted version of the console to allow the user use it on other processes (with restricted I mean locked for certain processes and cut off from certain aspects)

- Detection of virtual memory addressed by process (and automatic optimization, if possible)

- Memory lock for unstable engines (good ol' X-Ray cited again, but also others like Source...if you played Vampires - The Masquerade Bloodlines you'll understand what I'm talking 'bout)

Don't forget to leave your opinion in the comments, and feel free to speak any suggestions out loud, Stalkers.

Regards, YeiZoneX @ CreepDev -> a group led by giant rabbits and brown unicorns with no horns.

STALKER Clear Sky music... and more.
S.T.A.L.K.E.R.: Clear Sky

STALKER Clear Sky music... and more.

4 years ago S.T.A.L.K.E.R.: Clear Sky 3 comments

I have completed the music overhaul for Clear Sky, as well as a couple of other things I have been working on.

Absolute Nature 2 for S.T.A.L.K.E.R. Clear Sky
S.T.A.L.K.E.R.: Clear Sky

Absolute Nature 2 for S.T.A.L.K.E.R. Clear Sky

4 years ago S.T.A.L.K.E.R.: Clear Sky 11 comments

Tired roaming all the same looking Zone? Choose from 5 different styles. Each area can have unique ground and foliage textures.

Call of Pripyat music expansion released
S.T.A.L.K.E.R.: Call of Pripyat

Call of Pripyat music expansion released

4 years ago S.T.A.L.K.E.R.: Call of Pripyat 0 comments

That happened quickly; 53 minutes of new music to aid your immersion in the zone.

One project ends, another begins
S.T.A.L.K.E.R. Shadow of Chernobyl

One project ends, another begins

4 years ago S.T.A.L.K.E.R. Shadow of Chernobyl 11 comments

Because what's a horrendous wasteland without music? Shadow of Chernobyl music expansion.

Add game Games
S.T.A.L.K.E.R. Shadow of Chernobyl

S.T.A.L.K.E.R. Shadow of Chernobyl

2 weeks ago Released 2007 First Person Shooter

In 1986, the world's worst nuclear disaster occurred at the Chernobyl power station. Soviet authorities established a 30km 'Exclusion Zone' around this...

S.T.A.L.K.E.R.: Call of Pripyat

S.T.A.L.K.E.R.: Call of Pripyat

2 months ago Released 2010 First Person Shooter

Call of Pripyat takes you once again into the vicinity of the Chernobyl nuclear reactor that exploded in 1986. This so-called "Zone" is a highly contaminated...

S.T.A.L.K.E.R.: Clear Sky

S.T.A.L.K.E.R.: Clear Sky

4 months ago Released 2008 First Person Shooter

A group of stalkers, for the first time, reaches the very heart of the Zone-the Chernobyl Nuclear Power Plant-and triggers a cataclysm on the brink of...

S.T.A.L.K.E.R. Build 1935

S.T.A.L.K.E.R. Build 1935

1 year ago Released 2004 First Person Shooter

This is build 1935 of S.T.A.L.K.E.R. Shadow of Chernobyl, formally called S.T.A.L.K.E.R. Oblivion Lost. This was made by GSC Game World before they remade...

S.T.A.L.K.E.R: Oblivion Lost

S.T.A.L.K.E.R: Oblivion Lost

4 years ago Released 2002 First Person Shooter

Ones of the first concepts of S.T.A.L.K.E.R Shadow of Chernobyl.

Post comment Comments  (20 - 30 of 65)
ice_trey Jun 19 2011 buried:


worst engine ever, unnecessary ugly, nonoptimizzed , crashfriendly like nothing before, avoid if your a SERIOUS game/modder/developer

-7 votes     reply to comment
λpone Online
λpone Mar 2 2012 replied:

This man is on drugs don't listen to him

+3 votes     reply to comment
Rolfisalinas Aug 13 2011 replied:

"crashfriendly like nothing before", i'm asuming you havent played fallout 3 or new vegas. I gave this engine thousand of hours ussing it and it only crashed a few times when i moded my game

+2 votes     reply to comment
Opinionator Aug 24 2013 replied:


+1 vote     reply to comment
nocturni Oct 24 2011 replied:

Uh. Fallout 3 uses Gamebryo. Not X-ray. You are mistaken.

+3 votes     reply to comment
Rolfisalinas Aug 13 2011 replied:

"crashfriendly like nothing before", i'm asuming you havent played fallout 3 or new vegas. I gave this engine thousand of hours ussing it and it only crashed a few times when i moded my game

-2 votes     reply to comment
Derranged Jun 29 2011 replied:

OK, I want to see you create an engine as good as this one?

+1 vote     reply to comment
Sotoku Apr 22 2011 says:

I recently tried to replay my fully patched retail clear sky again, but when I try to run it, it says xrengine crashed.

Should I download the latest version to see if it helps?

+1 vote     reply to comment
Aggregate Apr 12 2011 says:

Wait, what? There's going to be a STALKER 2?

Best. News. Ever.

+5 votes     reply to comment
Sebo_hasee Mar 28 2011 says:

is it right that this engine has some codes from the source engine ?

0 votes     reply to comment
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GSC Game World
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Released 2007
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Mar 23 2011 by .sverek

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