Causality Effect

for Half-Life 2

2nd April 2006

Sci- Fi Single Player First Person Shooter Games Half Life 2 Doom 3 Far Cry Unreal UT2004 Quake Mods

What if everything that went wrong on “A Red Letter Day” was not caused by what you thought? What if your teleport ripped a hole in space and time? Now you must travel through time to correct the events and set right your past.

Causality Effect: A Red Letter Day Gone Wrong!

Text and images taken from the author’s homepage

Basic Details
  • Title: Causality Effect
  • File Name: causality-effect.rar
  • Size : 27.9Mb
  • Author: onboarderror
  • Date Released: 07 February 2006
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Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Single Player First Person Shooter Maps and Mods for Half Life 1, 2 and 3
Reader Recommendations
Avoid It!
Think Twice
Play It Later
Play It Now!

14 recommendations, average score: 4.29 (out of 5), standard deviation: 0.78 (what's that?)
Total Downloads

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Meta Review Data
Statistics based on 1 comment(s) with meta review data.

Using Gauge: Users
Manually: 1 Users

Time Taken:
Average: 0 Hours, 20 Mins
Shortest: 0 Hours, 20 Mins by Daken50
Longest: 0 Hours, 20 Mins by Daken50
Total Time Played: 0 Hours, 20 Mins
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  1. dougjp

    What can I say, except its a superb mod. Visuals, gameplay balance, everything. Beta testers for future mods/maps should compare the gameplay feeling against this one. A must download!

    Thanks very much!

  2. Mike

    I agee with the above. A great mod with plenty of variety with regards enemies, environments and atmosphere. Other modders take note: zombies are not the only fruit, right? I did have some quibbles, such as the loooooooooooong loading times, which at times had me wondering if my PC had frozen. And enemies not taking damage if you were trying to kill them from an adjacent area i.e. shooting them through an open door or gateway. But yeah, a great mod. Up there with the very best of ’em.

  3. Mikko Sandt

    Not bad – a nice little mod that suffered a bit due to the long level loads.

  4. Noswal

    In the middle of playing this and typing this while another level slowly loads, the only fault with the mod.

  5. The Abandoned Workshops

    The mod starts with how the “Red Letter Day” chapter in the game originally starts. However, things change during the teleportation process and you appear in an alternate timeline. The mod is mostly action from then on, both small and large fights with combine soldiers or striders which can be tricky to beat at times. Around the start of the mod, the author throws a lot of combine soldiers at you near one of the gates you open which is very challenging to get passed. Further in, the fights do get slightly easier but harder again near the end. During the play through you get teleported about in the past and future to see events happening which can confuse you at times, but interesting. There can be too less ammo and health at some sections but enough much later on. The mod also has four different endings, depending on who you kill near the end and some seem interesting.

    Very much like how Valve designed their levels which a good structure throughout many
    of the levels yet a few aren’t. A lot of areas tend to however be very blocky, especially the outside locations which was a shame. Props have been used well and not over done and fit in the location they?ve been placed. Texturing is also fine, mixing well with each other and the room type but nothing too special. Lighting is above average and always has a light source somewhere which is good, sometimes accurate to the type of light model it was. Many areas are very open spaces, plenty of room for combat and pretty much detailed so they?re not too empty.

    An interesting alternate timeline to play through with tricky gameplay and above average design.

    Rating: 75%

  6. jon

    DO NOT DOWNLOAD – this “mod” is full of bugs, it caused a full system crash and I needed to reinstall windows. This has never happened with any other HL2 mod/game. DO NOT USE IT, IT WILL BREAK YOUR SYSTEM.

  7. DO NOT DOWNLOAD – this “mod” is full of bugs, it caused a full system crash and I needed to reinstall windows. This has never happened with any other HL2 mod/game. DO NOT USE IT, IT WILL BREAK YOUR SYSTEM.

    Whilst I respect your opinion and lament your problems, you are the only person who has reported a potential problem with this mod.

    I therefore suggest readers download this mod but ensure that you have recent and verified backups of important data.

  8. I played this one 4 month ago and didn’t encounter any problem

  9. Egon_Freeman

    I haven’t had any problems. ^_^ It plays great. The only thing I do NOT get is how to get a different ending? If I have the chance to shoot anyone through the portal field, it does them no damage, so… :/

    Anyone has a clue?

    And, all in all, a great mod. 🙂 A bit slow to load, true, but I’d put the blame on my anti-virus software rather than anything else. 🙂

  10. The map loads were pretty slow but not uniquely slow. My anti-virus software is not to blame.

    This mod made hl2.exe crash on me in at least two different spots, in two different maps. One spot in particular was very bad in this regard–hl2.exe crashed at least 6 times in the same spot.

    There is no reason a crash of hl2.exe should damage anything on your system. I can’t possibly imagine how that would happen as a direct result. This is absolutely not meant to contradict advice to backup before running any new software.

    While playing this mod, the flashbacks left me clueless. I had no idea what was supposedly going on.

    The mod wasn’t too terribly difficult, but a couple spots annoyed me a bit. I look forward to the day I find a map or mod that doesn’t include a puzzle every three steps.

    *** SPOILER ALERT***

    If you haven’t played this mod, you may not want to read what follows, as it contains minor spoilers. (I like to err on the side of caution where spoilers are concerned.)

    On the last map, I killed Breen and Alyx (yes, sigh, Alyx) where they stood, yet they were marked as “M.I.A.” at the end. Dead isn’t “MIA”!

  11. The *** SPOILER ALERT*** is still in effect…

    I forgot to mention the problem I had with the gunship–the one that appears right after the first Strider is taken out. I fired no fewer than 18 rockets at that thing, thinking I was supposed to take it out (well, some mappers make them that difficult to take out!). Only then did I realize that part of the map was a gauntlet, and the gunship couldn’t be taken out. This was very annoying.

    Then there was that one spot where a map load occurs, and unless you’ve already taken out the headcrabs by firing at them below, you’ll be facing enemies right as soon as the map loads. Another one of my pet peeves…

    I didn’t hate this mod; I actually liked the level design. I just encountered a few things that really tend to drive me nuts. 🙂

  12. jon

    I have seen a few people have been questioning my “Do Not Download” thread, thats fine, I should explain.
    Firstly: I know I know ALWAYS backup etc but nobody is perfect, ergo I hadnt.
    Secondly:(in game)I had just exited on the surface after awaiting a longer than usual (even for this mod) level load, there were striders in the distance and a destroyed cityscape all about me(maybe someone knows where this is). This is all I saw as a few seconds later I was staring at the “the blue screen of death” with what I was being told was a memory violation. The usual ESC key and what not did not work so I had to reboot. Now ive been in this situation before but never through HL2, anyway the long and the short is, it wouldnt reboot at all not even safe mode, couldnt repair with the XP disk etc so had to clean install – boo hoo.

    So good luck to anyone playing this mod, one which I found quite fun tbh, but BUYER/DOWNLOADER BEWARE – it can hurt your PC.


  13. The mod didn’t hurt your PC; the problem must be a problematic video (or other) driver. A video- and processor-intensive game can help induce such a problem, but it’s still not the direct cause.

  14. jon

    “the problem must be a problematic video driver”

    U are correct HL2 is an intensive program, but why may I ask, after many (and I do mean loads) happy HL2,CS:S,other mods and EP1 (more intensive than HL2) hours does this mod crash after only a short amount of game play?

    It is highly likely that this mod is the root cause of my crash – not any lack of processor capacity.

  15. It is highly likely that this mod is the root cause of my crash – not any lack of processor capacity.

    No, I didn’t say it was your processor capacity at fault.

    I guess it is possible the mod is making hl2.exe do something extraordinary that would make Windows crash (maybe opening far too many file handles or something nuts like that; I have no idea). Looking at what the BSOD text says (especially if it mentions a file/driver name) would probably be the best way to tell.

    I know how aggravating and frustrating stability issues can be, so I didn’t mean to add to that for you in any way. Sorry.

  16. Egon_Freeman

    Problem with seemingly “random” crashes is that it’s really hard to track down the cause, especially when the computer in question is known to be running smoothly overall.

    But. There are things users are mostly now aware of, such as dust piling up. Those problems are, in themselves, not so severe, but can lead to nasty crashes when combined with ie. very high system utilization (abnormally high, in this case).

    Besides, it doesn’t take much to create a problem the only solution for which is a reinstall. It just takes the CPU making a small mistake in a crucial moment (ie. modification of some system file), and it sets a chain reaction resulting in a permanent crash. And it doesn’t even have to be the mistake itself to cause the crash – the PC might’ve been simply interrupted by the BSOD.

    By the way, Jon – are You sure You’re telling us the whole truth here? 😉 WindowsXP doesn’t HAVE a “esc key quit” functionality for Blue Screens of Death – a BSOD in NT-based systems means the system has ALREADY been halted, and there is no recovery possible (apart from a reboot), so hitting the ESC key wouldn’t do ANYTHING. On the other hand, the ESC key is known to help in these situations with Windows 98. And since Windows 98 is not really the platform of choice here, I would expect errors such as this to occur.

    So what’s the whole story? Because I’m confused.

  17. Yeah, you’re right about the stress applications can apply to the system. Sometimes an application can use more memory than has been used in a long time (if ever), and if it hits a portion of RAM that is faulty, it can induce a crash. This isn’t (directly) due to application bugs, though, it’s faulty memory.

    As far as I can think at the moment, system files needed to boot aren’t ever written to, other than the registry, and it seems pretty unlikely for that to be the cause. Even if the machine hive became corrupted (somehow…), the “Last Known Good” function should help.

    I’m going to unsubscribe from this thread because arguing about this isn’t on my list of things to do today. 🙂

  18. Mel
    Play It Now!

    Once again your teleport experience ends in mishaps, but the events unfolding are far different.

    I enjoyed this romp across City 17 with its street battles and sewage system encounters, ending with major engagements against the might of the Combine’s hardware.

    The mix is typical City 17; navigating through stressed-out apartment rooms and stairways with lurking Combine, progressing to the first of 3 or 4 well staged street battles. The leap into the sewage system brings with it different encounters adding to the gameplay, with one very tough encounter against alien form, mixed with the more mundane, find the button then search for the door routine. The final encounters are on a grand scale, whilst challenging you are afforded plenty of weapons, ammo and health.

    Causality Effect does not offer us anything new in the way gameplay, architecture or playing experience, it’s more a mix of well tried scenarios aimed at giving the player an hour or so of fun. It does however relay flash-back sequences to cleverly scripted events and twists from the original HL2 story after the teleport mishap. The twists are interesting, but you need to find them out for yourself.

    The general gameplay is fine with a good mix of foe and Combine hardware; puzzles are sparse, what there are being typical navigating and button finding. In the main the mod is not difficult and depending how well you overcome one encounter in the sewage canal, should take about any hour on easy.

    Textures and attention to detail were adequate with nothing outstanding, much the same can be said about the architecture of the street settings. I encountered no technical issues with the mod, with smooth play and game flow throughout.

    Negative Points
    – Nothing new

    Positive Points
    – A fun play

    An enjoyable play and fun while it lasted, nothing new to stretch the average player but well worth the download and play time. The flashback sequences were well compiled, adding interest and enrichment with plots and twists to the original HL2 storyline.

    My Recommendation

  19. My initial try to load the game was at the seven minute mark when I gave up. Will try again.

  20. Play It Now!

    I extracted it again and it loaded just fine after that. Turns out I had played it before and will give it an okay rating.

  21. Darth Marsden
    Play It Now!

    Fun little mod, even if the final fight is bloomin” impossible! Three Combine ships? Ouch!Very well made, it really feels like you’re back in City 17, which is great. Some of the battles are tricky, mostly the ones against striders and combine ships, which come in pairs and really hurt. Still, it’s a challenge.

    Good level design, interesting plot, great gameplay…

    On a side note, I don’t think it’s been mentioned here HOW you get the different endings, just that you can. So…

    To get different endings, load the last autosave of the game. When you come out of the corridor, you’ll see Alyx and Breen run off. Which ending you get depends on whether they survive or not. If you want the best ending, kill them both – if you slowly edge out of the corridor, you can just see Breen’s head over the air-vents, so you can cap him one (or three) with the pistol, leaving just Alyx to take out with a double shotgun charge.

  22. Zockopa

    The intro and the first battle are well made, but afterwards there are a couple – in my opinion – wrong decision made gameplaywise. For example the gunship that only goes down after zillions of rpg-hits or the antlion queen who is only vulnerable in a arena fight. Sorry, but that is just poorly done. It felt insincere.

  23. Apply
    Play It Later

    From what I remember I thought this mod was a 8/10

  24. Lars
    Play It Now!

    I liked this one. Yes, it has a few bugs, and the loading is slow, but the level design is clever and the gameplay is interesting.
    I found the final showdown just right — pretty challenging without being too frustrating.

    Feedback to author: there were a number of places that I apparently couldn’t go even though I could. Know what I mean? I could climb up there, but apparently I wasn’t supposed to, because the game didn’t let me go there, even though it looked like a place I should be able to walk. Like I ran into a glass wall.

    Anyway, all around lots of fun.

    On the other hand, don’t play with Alyx’s loyalty. I didn’t like that twist.

  25. Taaha B.
    Play It Now!

    wow this mod was great. great gameplay and everything. I thought it was gonna be really short because it only had one map when you click new game, but boy was I wrong. everything was great about it except that in my opinion I think it was more graphically intensive. my fps in some places went down to the 20s and 30s which is weird because usually my fps stays in the 40s and above. the final fight was challenging. I had to use a shoot and cover tactic where I would shoot one rocket and then duck after it hit. then I would wait for an opening. luckily I was hiding where the medstation was. the different endings were interesting with number 2 being the closest to the original timeline. though I wouldve liked it better had number 2 been exactly as the original timeline. overall great mod. 9/10.

  26. Ollo
    Play It Later

    it’s definitely worth playing despite one or two flaws (couldn’t get the helicopter in lev4 down even after 15 rockets). well done, much like the original levels!

  27. G
    Play It Now!

    Great game, will play again, although I’m not sure about some of the aspects of the game. I’m with lars on not liking how Alyx was a traitor, but it was still an interesting thing to see. I also didn’t enjoy the long loading times either, but that also may be due to my laptop not being built for gaming. Also, as far as changing the story line is concerned, I’m not sure how shooting alyx or dr. breen would affect the past. And when you are in the flashbacks, when you try to save your friends like barney or dr. kliener by shooting the combine there, the bullets just hit them but do no damage. One of the comical things I noticed was how all the phrases and conversations were straight from the game. Sometimes it didn’t fit in like when you are in the flashback where dr. kliener and barney are discovered by the combine, barney shouts get away from there, which just doesn’t fit, along with the end where alyx takes you to the combine in the beginning. But still, it was a great use of the the original voices, and all in all a great game!

  28. MurphyX

    I didn’t understand the ending… Ending 2 of 4???

  29. zarathustra

    Not a bad effort, this MOD.

    I’m posting mainly to say to “Jon” that definitive statements like “DO NOT USE IT, IT WILL BREAK YOUR SYSTEM.” have absolutely ZERO value when the vast majority of players will experience no problems with it whatsoever – me being one of these. I had a fault-free play, although I would concur with the ‘long load-times” comments.

    Perhaps you should have relayed your feelings a little more personally; “I found this MOD to be instrumental in BSODing my PC”, or “I had a full system crash whilst playing this MOD, although it may have been unrelated” seem far more mature & helpful than “DO NOT PLAY!”

    Think how hard the devs have worked in getting this MOD to release status. Do you really want their struggle to be completely ignored just because one(!) user has had a hissy fit after unknown, & quite probably random, difficulties?

    Come on!

  30. Acr0nym

    Much fun, yet too short. Nothing to me appeared incongruous. The last fight is challenging. Thanks for making this.

    I had no problems running this on my VERY overclocked (2.13Ghz c2d @ 3.2Ghz and HD3870 @ 830/1211) system. I do get a BSOD on rare occasions which I put down to my overclock, even though I do have quality components in my system. But not a single problem with this mod.

  31. Jeff
    Play It Later

    I liked the concept of a time fracture, but it all seemed a little random. Didn’t really understand the alternate endings, but there was a lot of good gameplay in this mod, so I can’t complain!

  32. Play It Later

    It was a nice mod, and you felt the mappers progress in mapping. He now even works in the Black Mesa Mod Team!

    To the mod: Well placed enemies, stupid allies, Cool story, Confusing story… :S

    It all comes together to something you’ll actually have to play yourself… I can’t really explain too much, as I was confused myself with the timeline… And I was surprised Alyx betrayed the rest. Now we know what the Author thinks. 😉

    However the end is werid…

  33. gsp1995

    I’ve played it a long time ago, and I sure want to play it once again, because at the time I played it, I was only 11 years old. I want to play it again =D but the download link isn’t working =[

    1. Thanks gsp1995. I’d clean forgotten about this mod. it’s a good mod and not saved in my Sourcemods folder.
      I can’t get the link to work either.
      Found a download here:
      I’m off to go and play.

  34. Play It Now!

    This is a very good mod with great combat.
    Marvellous boss fights especially in the last map. I wanted to take on the Helicopter as well but it did runner – what a chicken.
    The end was a bit odd but ignorable so did not detract.
    I’ll be playing again

  35. Milkbone

    I just tried to dl ce but it wasnt on server so it sounded familiar and I searched ma hd and found it. Installed it and started it and remembered playing some of it before. Then when I got to the room after you bust up the concrete wall over the pipes with headcrabs and an infected human I remember this is where I stopped before. For the same reason Im stopped now. I cant seem to find my way out. I have the ladder leading to the roof but it so far up I cant seem to pile stuff high enough to reach it. But as far as game play I like it and wish I could finish it but as for now I gonna haveta put it on a back burner again. I feel so stupid, I usually figure these things out but I stumpted on dis one.

  36. Milkbone

    Man I am really stupid because I dont know what I did different but I replayed it again but this time the door opened for me and I finished the episode. It was ok and it said I finished 1 of 4 possible endings.

    Do the endings change each time you play?

  37. Play It Later

    I’m not sure. I loved the gameplay, and the background elements! This is a great mod to play if you don’t care about the storyline. The storyline was okay, this could happen.
    But what could never happen is Alyx joining the Combine, she’d never do such a thing. That’s just not Alyx, she’d never want to kill Gordon or her father.

  38. Where I Can Download this Mod?

    1. I’ll try to make a download available soon.

  39. Think Twice

    Great looking mod. Game play, not so much. At every turn they throw the kitchen sink at you. Right off the bat you fight off half a dozen combine and a gunship with 100 rounds and no rocket launch. That is until the useless NPC dies and drops it. Then you open the big gate and get rushed by over a dozen combine. There is a mounted gun but it’s so close to the gate you take heavy damage. Later on you fight off 3 gunships while stuck on a roof. FYI you can just copy the maps to your HL2 map folder and use the console to load them.

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