Half-Life: Xen

21st July 2012

The Replay Experience Experiment: Half-Life: Lambda Core

Gordon Freeman arrives in the borderworld, Xen.

On the strange borderworld, Gordon encounters many of the aliens that had been teleported into Black Mesa in their natural habitats, as well as the remains of HEV-wearing researchers that came before him.


No trivia for this chapter. Do you have any?

The Poll

This poll is only about the XEN chapter, not Gonarch’s Lair etc.


The challenges below have been set by 2muchvideogames

  • Destroy all 4 purple laser lamps.
  • Find the hidden medikit on the large island.

MEDIUM: 17 Health 0 HEV [25KB]

HARD: Coming soon.


Click on the thumbnails below to open a 1024 pixel wide image.
WARNING: The screenshots contain spoilers.

The Replay Experience Experiment: Xen The Replay Experience Experiment: Xen The Replay Experience Experiment: Xen The Replay Experience Experiment: Xen The Replay Experience Experiment: Xen
The Replay Experience Experiment: Xen The Replay Experience Experiment: Xen The Replay Experience Experiment: Xen
The Replay Experience Experiment

This post is part of the The Replay Experience Experiment 2012 event. This is a chance to replay all the Half-Life games and discuss them based on our experiences since we first played them.

Hat Tip

All text taken from the CombineOverWiki, a fan-supported, editable wiki covering the Half-Life series of games.

A Complete Half-Life Walkthrough
A Complete Half-Life Walkthrough

On the left is a complete text walkthrough for Half-Life.

It has been written by Stanley E. Dunigan and updated with all the tricks and tips from PlanetPhillip.Com readers.

It is in PDF format, meaning you can open it directly in modern browsers or download it and print it.

(Left-click to open and right-click to save)

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  1. Summary

    I consider this a rest chapter. Valve introduces the world without too much action. I only killed one vortigaunt and a handful of houndeyes.

    The purple laser lamps are there to keep you on your toes. I have to admit I had totally forgotten about those.


    I suppose that this is just a jumping level really. Nothing difficult at all, unless you try and get clever.

    Simple puzzle with the portal at the end, but nothing to worry about.

    Points of Interest

    Nothing, just 10 minutes of exploring really.

    G-man Sightings

    Can’t believe he is in this chapter!

    Bugs or Errors

    None that I noticed.

    The Poll

    Yes, once.


    – Destroy all 4 purple laser lamps.
    – Find the hidden medikit on the large island.

    5 Words or Less Review

    What have I been smoking?!


    10 minutes



    1. G-man Sightings
      can’t believe he is in this chapter!

      What do you mean? he is not.

      1. What! You didn’t see his head peeking about one of those Xen chimneys?

        1. no. You must have had an hallucination or someone is trolling you. Or maybe you’re the one trolling us 😛

        2. pics or it didn’t happen

  2. One of the game’s shortest chapters, this one is made to introduce the alien world, Xen, to us. When, long time ago, I saw Xen for the first time, it was very stunning, interesting and inspiring, because I never saw anything like that before, it eventually inspired me to create Xen locations myself, but, unfortunately, I couldn’t make the Typical Disaster’s Xen as great as the original one. I was pretty happy with it anyway, though. 🙂

    We use our long jump to jump from island to island, then, using some flying cones, we get to the big island, inside of which there is a teleporter which gets us to the next chapter. Finding the way inside is an environmental puzzle.

    There are pink lights which shoot at us with lightning, and there are houndeyes. One of them starts to jump around when you kill it, you can see it in my “Half-Life Source Fun” video. I wonder what could cause such glitch. Healing puddle is a new mechanic which is introduced to us here.

    Playtime: 4 minutes

  3. 2muchvideogames


    This map, while helping players get accustomed to this strange, new, border world, is also the grounds for long-jump testing. The player’s recently acquired longjump module will be put to use here (and later on too). A large jumping puzzle involving the long jump, from floating plat to plat, will make players become familiar with long jump, hopefully. No other game in the Tree event will involve the long jump, so get comfortable with this one, because it’s the only one you’ll ever get.

    Playtime: 03’04”

    P.S. G-man is everywhere. Always. He’s obviously hiding somewhere that the player will never find. He could even be watching you from inside your own HEV suit! That suit of yours is full of tracking devices.

    1. He could even be watching you from inside your own HEV suit!

      lol I dunno if I should think this is funny or creepy

      That suit of yours is full of tracking devices.

      That just made my day 😀

      1. Ade

        It’s a scientist’s line..

        that suit of yours is full of tracking devices

        1. I know, that’s why it’s so funny. It gives a whole new meaning to this line.

  4. XEN
    All the little butterflies, they are free
    Since the controls on the Dreamcast version are balls, I will be playing this on the PC using the Dreamcast mod. This is probably the most hated chapter in Half-Life, but I really liked it. People say that this part is too hard and you have to start over whenever you fall. Do these people know about the quicksave and quickload buttons? The jumping puzzles were fun. This was the shortest chapter. I got the first challenge. There were no differences in the Dreamcast version.

    Playtime: 3 Minutes
    5 Words or less: Fear and Gravity

  5. Xen, the first chapter on the borderworld. It’s actually a very short chapter, the first one that I actually completed under 1 minute 😀
    We start off after teleporting, on some random floating piece of land, showing us right off the bat that xen physics are weird. it may seem impossible at first to reahc other platforms, but we soon discover the new gravity. We should normally use our longjump module right now, but I didn’t take one 😛
    I assure you, all the jumps are possible without longjumping, I used the gauss to skip straightforward to a further island. We soon realise that aliens are teleporting here also, so this is not the main location of xen, and the aliens come from somewhere else. when we reach the big island, we have to jump down and encounter some weird purple laser turrets. They have a lot of hp, so better run than try to fight them (or just stay a few feet away, their range is low). we also see the health regen pools, to show us that even without the chargers we should be okay in xen. then we get IN the island, free some floating things that I cannot identify, open some objects also unidentifiable, then the floating things go in, start a laser and open a portal. pretty weird, but hey it works so who am I to complain?

    i didn’t die 😀

    Five words or less review
    I love that new gravity

    46 seconds and 458 milliseconds


    Wow I didn’t even realise that this chapter was so short! Well short size wise as even getting down from the starting platform was a chore, thank goodness for the healing pool.

    Time wise, not counting Black Mesa Inbound, this was the shortest chapter for me so far!

    A nice little feature is that the Houndeyes don’t seem to attack you unless provoked or you get too close, at least I believe this is intentional.

    Challenges: Destroyed all 4 purple laser lamps and found the hidden medikit on the large island.

    Playtime: 9 minutes

  7. Unq

    The shortest chapter in the game. When people talk about Xen even as a chapter, they’re usually thinking of the entire set of maps from here to the end of the game – the bulk of which are actually in the Interloper chapter.

    This is only one map, and it’s not a terribly challenging one. It’s meant to give you a gentle, non-threatening introduction to the last act of the game. It’s different than everything we’ve played through before, although we’ve been seeing bits and pieces of Xen ever since the resonance cascade (and got a quick visit there during the actual cascade). There are only a couple enemies here, of the weaker variety, so they’re easy to take down.

    But more than anything in this chapter I started to feel out of sorts – it’s an alien world and I felt like an intruder. However it’s clear to us that we’re not the first visitor here – on the very first island we jump to we find a dead scientist wearing an HEV. The plot thickens.

    Mapper’s Corner: Besides gravity, our new adversaries in this map are the Xen flowers. They’re really just annoyances but they’re a nice little trick to examine, since they’re not enemies per se but are a combination of map entities instead.


    These are actually set up by the mapper just like the Xen laser turret was back in Forget About Freeman! The basics:

    – An invisible func_tanklaser set to start active. This entity sets things like the sound to make when firing (ambient_generic), the range of the laser, how far up/down it can see, how accurate it is, etc.

    – An env_laser that is referenced by the func_tanklaser. The env_laser actually makes the laser beam and does the damage; its target is set to the player.

    – The body of the flower is a func_breakable that is set to flesh material so it sounds like we’re shooting something living. Once you do enough damage, the func_breakable breaks and targets the func_tanklaser which turns it off.

    – As a finishing touch, when you kill the flower there is a small puff of purple smoke (env_sprite), and the subtle purple lights near the flower go off (actually light_spots in this case).

    Playtime: 4 minutes, mainly because I tried the fancy gauss jump a few times in vain

  8. William

    Playtime: 11:47

  9. Ade

    Was reading the poll and went: “why would anyone die here” then I remembered how hard the long jumps were for me, too, a long time ago 😀
    I forgot to read the challenges before playing this chapter so I didn’t bother destroying the tank-like chandeliers, but I did find the health pack.

    Playtime: 6 minutes

    I wandered around in hope to find other (secret) areas but there weren’t any..

    5 Words or Less Review
    Is that it?..

  10. Hec

    I wrote this on the Xen walk mod review:

    Overall I’m being quite subjective on this one, because I don’t particluary enjoy Xen map style, to me Xen also was like a Valve experiment to recreate “open areas” or open spaces inside HL1, thing that due to the tech limits of the time was not achived, so the open areas xen couldn’t fulfill, are suplied by strange high caves and narrow tunnels, quite similar to Black Mesa but with xenian textures.

    I feel that’s not only how I feel about Xen but also describes valve attempting to give their especial touch to HL1, as BM was alredy a limited location to develop all the game, they needed another environment to close the gamer amusing feeling inside the HL1 title itself.

    Is also curious HL1 ended at Xen and we have never seen Xen again in HL2, maybe in HL3??, who knows??, is crazy but could be cool, I don’t know why Source developer modders, never have experimented trying to recreate Xen in Source(setting APART the HL2 cool and very recomendable “Transitions” mod), with all the wider possibilities that engine brings, it would be just delightful. But sorry, with the original HL1 engine I just don’t feel Xen is my place to be or to play and have fun inside HL.

    1. Hec

      Is also just eagerly and quite mysterious how the Black Mesa Source team, attempting to recreate HL1 in Source is going to present Xen…., I just can’t imagine, is perfectly possible, but I think this is going to be a big event in HL mod history indeed.

  11. Tudor Ionel

    I remember this chapter well, in every detail. When I’ve played it first I was amazed at the skybox scene, and the vegetation (and fauna) on Xen. I remember we used to sit for a long time in the healing waters to hear that serene music. I couldn’t bring myself to go through this fast, I wanted to explore every bit of the levels and see and hear everything, because I did miss a secret and some few architectural details.
    We are not alone, afterall.

  12. No mono/dialogues here.

    Ugh, Xen! Fortunately this is only a short chapter hehe, it only contains a flying island if you want so. To get there we have to do longjumping to smaller, floating in circles islands to descend to the large one.
    So the introduction of this foreign, remoted place looked quite pretty and interesting to me back in the days. The island is quite nice and I like the sky, but that’s almost it already.

    Longjumping is not made for me, I remember when playing the first times I did fail so hard or maybe even didn’t know that there’s a longjump required, I can’t remember.
    Because at first I guess I simply forgot that the module is offering longer jumps than usual so I guess I cheated often there. However, it’s of course clear now and it also was some day at the first playthroughs, but I’m not good in longjumping, my timing sucks.
    Although, I can remember that many years ago it worked just fine as the timing is usually right.
    Whatever 😛

    There are a few little surprises here, such as the spawning aliens when landing on a platform and the purple laser lamps that start shooting you when coming too close.
    Who would have expected that the first time?

    Inside the “fortress” is a tiny puzzle to solve for using the teleporter. Besides, it’s very simple and easy I like that puzzle. It requires to jump on some ledges to reach the switches.
    It would have been better if there’s only limited time to hit all 3 of them to make it a little tougher, but don’t ask me how to realize that without making it too unrealistic or weird.

    The atmosphere in Xen chatper is nice, there are ambient sounds, neat design for the island good use of colors.

    Challenges were too easy this time hehe, but okay, there’s not much else anyway.

    Poll: Voted yes, actually…well, see below 😉

    Deaths: None, I just quickloaded fast enough when longjumping failed 😉

    -Destroy all 4 purple laser lamps. – Okay, why not (poor pistol ammo!)
    -Find the hidden medikit on the large island. – Yes

    5 words or less review: Super Mario invented longjumps first!

    Playtime: 5 minutes

  13. Vic

    As Unq said earlier, when people typically talk about “Xen”, they refer to the entire progression through the alien borderworld. The term would have been less liberal in its definition, had Valve not decided to split Xen into two distinct chapters: “Xen” and “Interloper”.

    Yes, a quick look through the map filenames will reveal that Interloper was to start off directly after the last map in the Xen chapter. It’s an interesting choice, which I’ll try to talk about when I get to Interloper.

    The Xen borderworld itself is, as you can tell from the name, a pocket dimension which exists between the boundaries of other universes/worlds. In case you’re wondering, the wider… place housing all these universes and dimensions and worlds and zones is known simply as the “continuum”, as Wallace Breen was to reveal in Half-Life 2.

    In any case, the core idea behind a borderworld is a very interesting one, with great purpose in its conception – as we will later find in Half-Life 2, Xen (and, presumably, other borderworlds of its kind) is extremely important to the science of teleportation, where Resistance scientists manage to use it as an inter-dimensional slingshot, making localized teleportation procedures in the same universe, safer and more reliable.

    The borderworld itself is a uniquely intriguing and fascinating environment. The sound design is absolutely incredible: everything sounds distinctly alien, from the distant belches of sentient meteorological nebulas, to something as simple as the sounds of the wind. It is simply astounding.

    Xen’s art direction is also extremely original and multi-faceted. Much of it is inspired by the work of H.R. Giger, a Swiss surrealist artist known for his design work on Ridley Scott’s Alien. It all looks remarkably strange, oddly authentic in some way, and as distinctly hostile as a real alien world would be. I could keep going on and on about the sensibilities of Xen’s art style, but at the end of the day, it’s rather pointless, considering many of us already know it.

    I can only say that I wish Valve re-approached Xen, and gave it a second chance with all the amenities of modern game technology, modern game design, and perhaps improved upon its already excellent ambience and tone. And judging from leaked concept art for HL2: Episode Three dating from March 2008, they might just do that: http://tinyurl.com/lambdagenep3

    But for now, let’s put aside matters concerning either the narrative or the miscellaneous stylistics, and focus on the chapter at hand.

    Xen the chapter is an extremely brief chapter meant to quickly and concisely introduce us to gameplay in the “world beyond”. Already we can see the hallmarks of Xen gameplay: the irritating jumping puzzles. Back in those early days of game design, few developers had realized the innate failings of first-person platforming. As such, Valve didn’t realize how fundamentally awful this kind of gameplay is.

    The main problem with it is, of course, the fact that to accurately assess distances, perform precise jumps, and land with great care (tasks that Xen gameplay demands from the player), you need to see where your feet are. Setting aside the fact that you have no feet in Half-Life; it can be understandably difficult to look down and approximate your exact position, when you’re doing so while moving and aiming at a distant platform.

    Another problem is the arbitrary placement and elevation of the Xen asteroid islands. It can be very hard to tell which one is closest to you, both vertically and horizontally. As such, playing the way Valve wanted you to play can quickly become unfairly challenging, when you can’t even tell where you’re supposed to go.

    While one can eventually get trained in approaching and pulling off these kinds of movements, the platforming and jumping still inherently remains a trial-and-error kind of deal, especially for new players. And of course, all of the aforementioned weaknesses of this particular brand of jumping puzzle, still remain present. And that’s just not cool.

    This is why I think Xen gameplay should be less about jumping, and more about… exploring. Exploring perilous, fascinating, and oddly mystical alien landscapes. Numerous fan-made mods manage to pull off Xen gameplay using these kinds of approaches, and they do it very well. Blue Shift also manages to tackle Xen in a far more enjoyable and tolerable manner.

    Still, Xen the chapter only contains a teeny weeny bit of first-person platforming. As tedious as it can be, it’s relatively painless and it ends quite quickly, when we reach the massive shell island.

    Combat there is fairly tame, presumably because Valve expected most players to take some hefty fall damage on the way down. As such, we only encounter Houndeyes and strange crystal energy turrets. These turrets take far too much punishment before they die, but at least their attack distance is hilariously short, allowing you to take your time in destroying them. So it’s not really a problem.

    We enter the shell island itself, only to find what appears to be a Xenian portal. It feels strangely familiar in its aura of inexplicable mystery, and in the shades it casts of inherent mysticism, and fantastically alien ambience.

    This is in stark contrast with the ominous, nightmarish, technological monstrosity that was the Lambda Complex teleporter. Yes – activating this Xen portal is as easy as opening a few… clawed podium compartment things, and… unlocking three… energy butterfly things. It’s so subtle, so refined, and so sublime that, yes, words fail to describe the way Xen itself works – a sentiment that Wallace Breen himself will later echo in Half-Life 2.

    We cannot understand how Xen works – and I, personally, am really glad for that, because it augments the fiction in a unique and very intellectual manner. Besides, why pointlessly clutter the narrative with bland, pseudo-scientific explanations of how something works, when the very way that something works fundamentally depends on mystery and inexplicability? I think that’s what sets Half-Life apart from the rest – knowing what to tell you, and when.

    So – we activate the aforementioned portal, and step through. What awaits us on the other side? A confrontation with a monstrous, and somewhat disturbing foe.

    Play time: 7 minutes

    Five Words Or Less: Remarkably flawed, but remarkably unique.

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