One level – Played Two Ways.

18th June 2009

Single Player First Person Shooter Maps and Mods for Half-Life 1, 2 and Episodes 1, 2 and 3
I was shown a poem last week that was designed to be read from front-to-back OR back-to-front. It was in multiple languages too, but that’s not really germane. I’m not exactly sure whether sections are read in reverse or even how it works but it certainly got me thinking. I do know that the story is different, not just reversed, if you read it backwards.

Would it be possible to do this for a linear level?

I have played a few levels where when you reach a certain point there is some form of event and the player has to backtrack along exactly the same route. Normally the corridors are damaged, the lighting is different and there are new enemies etc. I’m not thinking of something so simple, oh no!

I’m thinking of exactly the same level but with two potential starting points; A and B.

Let me give you a simple example.

When the player starts from point A the level is all action, one big fragfest. However, when the player starts from point B it’s possible to play the level in Stealth mode. No enemies need killing.

Now, I call this the simple example because of the opposite nature of the gameplay. I am fully aware, even with no mapping experience, that making a level like this would be very difficult.

But that’s one of the reasons for this piece, to explore the idea. I honestly believe that SP mapping has many exciting new elements still waiting to be developed.

Let’s look at a more complicated example.

This one contains scripted events, the position of observance of those scripted events is very important. We’ve all seen films where one event seen from different positions results in completely different opinions.

Imagine a level where when you start from point A you encounter a situation. You hear plenty of shoot just before you witness anything. Then you “clearly” see rebel A shoot rebel B. Obviously rebel A is a traitor and must be killed. But if played from point B the same situation is viewed differently. Rebel A did shoot rebel B, but what you missed because of your position is that rebel B just killed a group of other rebels and is obviously a Combine infiltrator.

That example is off the top of my head and I have no doubt that with some collaboration between some clever mappers a much better situation could be constructed.

In fact, that’s not a particularly good example because it negates point A to the incorrect less-knowledge based one and I wanted something much deeper.

I wanted an idea where both positions are valid but cause the reader to view things differently, not necessarily contradictory or right and wrong.

The basic layout is not really important, two joined “S”s would be enough, it’s the location of the details, enemies and timing of events that really matter.

Depending on future projects I may offer some cash as a prize and open this up as a mapping competition.


  1. demoneyeoffire

    hmm… this sounds like a very good Idea, this will be fun…

  2. Kyouryuu

    A premise similar to this was used in the brilliant final level of Braid. Specifically, the idea that the level you saw moving forward has a completely different context when you see it play in reverse.

    1. Sounds like I stole their idea then. I don’t know the game you menion but were you able to play it from both ways?

      1. Kyouryuu

        Braid is basically a side-scrolling puzzle game that emphasizes temporal gameplay mechanics, such as rewinding and fast-forwarding time. It’s quite a gorgeous game, with amazing graphics, a melancholy soundtrack, and an intriguing storyline that makes it hard to answer your first question without spoiling something. 🙂

        It’s also on Steam now.

  3. Kasperg

    It also brings up ideas of playing with the temporal dimension. Imagine a map which seemed to end with a negative event. With the knowledge of that first playthrough, you are somehow transported back in time with more knowledge than before, and therefor are able to make different choices that have different results. I’m not exactly sure what the limit of those travels could be, but it certainly has the potential of becoming a big puzzle. Do I save that rebel or destroy that Combine cannon before it’s activated? That sort of thing.
    It could be something similar to the Star Trek TNG episode “Cause and effect”, in which the crew is stuck in a time loop but somehow little events and details stick with them through each time change until they figure out how to end the events that lead them to their doom every time.

    1. You should check out the german movie “Run Lola Run” (
      In it, the main character “gets several chances” to complete a task after failing.

      1. I remember that movie but to be honest I don’t remember the details except the soundtrack which was very intense.

    2. How does this differ from what happens now? We simply relaod from out last save point.

      Unless you mean something else. In fact, when I saw Next I immediately thought it was exactly what ahppens in video gaming.

      I remember that ST TNG episode, it was decided by the three pins on Riker’s uniform. Maybe that idea could be used wholesale. The is only one level but it is very detailed, the player has to achieve some particualr objective and the only way to reach it is by playing the level lots of times and noticing all the details and deciding which is important and which not.

      Of course, it’s not directly related to my idea but very interesting nevertheless.

  4. Gypsy Jim

    I never really got the hang of all the different classes of player, but I think that Substance kind of addresses this with the differences in Stealth vs Full-on kick-ass combat. I realise that the team behind it had different ideas than the one you’re proposing, but the ability to play the original HL2 maps with different powers kind of fits your thinking……..

    Kind of…..

    1. Not really, although there’s another idea I will post about soon.

  5. Dragonsbrethren

    TimeSplitters: Future Perfect does something like this using time travel. You play through a map, and at some point you’ll encounter yourself from the future. You usually have to defend your future self or something like that. Later on the in the map, you find a portal that will take you back in time and you play as from the other perspective, while your past self defends you or whatever. In one map you actually end up playing from four different perspectives, all in the same room doing their own thing.

    One of the last maps of the game is actually playing through the first map again, in a completely different area that was inaccessible in the original, making many of the first events you witness in the game happen. They kind of blew it by having those events happen in a different order than they did originally, though.

    1. I should mention that Kasperg introduce the idea of “time” not me. My idea is just one level and the player can choose starting point A or B. It’s more of an experiment rather than something that should be included in a mod or game.

      1. Tycell

        I dont know if I have misunderstood or somthing but I think the idea of choosing which way you go is used all the time. When I try to think of a level with this idea in I come up with somthing like so:

        [ ]
        [ ]
        [ ]
        x====A B====x

        So you start with a choice, either route A or Route B. One route means you have to sneak and dont get so many weapons, the other means more fighting – this idea is not that uncommon (But not used enough). For one thing stealth in Source is quite hard to pull off well without giving the player some new ability (like cloak or somthing).

        If you were to play the level from one end or the other like you desribed how would you have the end of the level at either end as well? Two starts should mean two ends right? You can do it with one end still but it would be tricky to do over and over and still seem plausable.

        1. Tycell, yes you have misunderstood. Using your text it would look like this:
          A >>>>>>>>>>>>>>>>>>>>> B
          A < <<<<<<<<<<<<<<<<<<<< B The only choice is the starting poisition. Also I used Stealth as an example rather than the ultimate goal. It could just be A to B=fragfest, B to A=tactical

          1. Tycell

            Hmmm… so instead then;

            So for example somone sneaks into a base to steal the HEV suit, and then once they have it all the alarms go off, so they have to get out (roughly) the way the came in, but now the alarms are up its no longer sneaking, speed or jumping that gets you by, you have to use force?

            1. No, not that either because that sort of thing has been done before. It’s more simple than that. Going from A to B or B to A is done in any order. Remember it’s not part of a mod, just one level with two start points. The player decides which one the start with. The idea is to try and make a level that is more detailed than it would seem.

              Imagine this: You are in a court room and there is a case going on. Witness Z played from A to B and gives their story, Witness X played from B to A and gives their story. Both are the truth but have completely different results. Who is correct? Well, both of course, it’s just highlighting that sometimes your point of view affects your truth or reality. There’s no right or wrong, just viewpoint.

              Or an even simpler example. There is a large hill. The bottom is labeled A and the top B. Runner Y runs down and runner W runs up. They both travel the same route and distance but obviously their experience is completely different.

              Hopefully that makes more sense.

        2. Xblah

          I’ve seen a map like this in Condition-Zero: Deleted Scenes.

          You were supposed to get into an office with those fiber-cams without being spoted. Then you should go backwards killing everyone. Actually, there were a lot of levels like that. And the camera thing can be easily coded in Hammer.

          1. I don’t think you understand my premise. It’s not an idea where you reach one point in a map and then go backwards.

            It’s one level, that is played in one direction and when you reach the end it stops.

            It’s just very different depending on which direction you play it. Like a hill. The direction is the same buyt going up is very different from going down.

  6. Passerbydroppingby

    In a way this is what HL2 Episode 1 did, making you start with the supergravity gun, rather than ending with it.

    I like the idea of a palindrome level.. but why just 2 starting points? One of the joys of the HL1 universe is that you can “officially” play it from 3 starting points (Gorden, Adrian & Barney) and thanks to the great modmakers you can also play it from very, very many different “unofficial” starting points (as alien slave etc).

    1. I understand what you are saying but the difference is the timing of those three protagonists. They are inter-related, things that happen around Adrian and Barney are caused by Gordon.

      I did consider the point of a plaindrome level but it’s only that way on a superficial level.

      Sounds like I am going to have to design/make this to fully explain by idea, pity I can’t map!

  7. Stratofarius

    There was a mod called Random Quest which was like that. You could kill the woman and get the battery, or kill the man and get the radio, or kill the vortigaunt, or serve him, or eat the watermelons, or don’t kill the master, or…

    1. No, RQ is not like this idea. I am not talking about choices within a mod or even a level, just the direction you travel in.

  8. MikeS

    Everyone seems to be over explaining and complicating this. It’s simple, really. Imagine booting up HL2:ep2 and being asked whether you want to start at the missile base and head for the train wreckb, or start at the train wreck and head for the missile base. Both would mean travelling through White Forest and the caves, but in opposing directions. Obviously, Ep2 wouldn’t be a good one to try this out as the player would be plunged into a frenzied Strider attack! But that would be the mod maker’s challenge — to make a map that works from both directions and — quite possibly — forces a different approach from the player…

    I imagine it would necessitate two BSP files — a BSP file where the player starts at point A, and a BSP file where the player starts at B. Same map, just different starting points.

    1. I don’t think everyone is over explaining it, just me. And I keep doing it becasue people don’t understand. Yes, two BSP, just with different starting points.

      It’s not “quite possibly”, it’s definitely. I am sure plenty of maps could have multiple starting points but my idea is about making sure that the outcome of playing at different ends is very different, not just in where you finish.

  9. Poison_Berrie

    The principal is interesting, but since the players is likely to go both ways eventually why not give each route a bit of information that complements the story.
    Something that adds depth or a new dimension to certain events, regardless of which side you picked first or viewpoint of the event.

    1. I don’t believe that the player is likely to go both ways. This idea is not cirectly related to being part of a larger mod, just a thought experiement in viewpoint and level design.

      1. Poison_Berrie

        Well I conceed that these musings are purely theoretical. If the player enjoyed the level/mod and this was the “gimmick” than it would more than likely that he will try the other route as well.

        1. I am going to try and build a simple implementation of this idea this summer. It will be my motivation for learning to map.

  10. Jasper

    Mission Improbable very nearly meets your specification.
    You can kill all the zombies on the way to the lighthouse and then fight the combine on the way back.
    Or leave a few zombies, especially the speed zombies as you cross the bridge, to give the combine something to do on your way back – great fun.

    1. Sorry Jasper but it is not even close to my idea. I have decided this is going to be my first map, sure it won’t be fantastic but I think the only way to truly explain will be to make it.

  11. Blue Lightning

    Firstly, I wonder why you have never asked for a highway17-water hazardville competition? You know, for those of us who love those driving sections of HL2? I would love at least a blog about it, and I could throw in some good ideas about the rules of it.

    Second: I have always had the idea that a water hazard two hour map could (after 15 minutes) have a fork in the canal…if you go left, you get a map load and cannot turn back. If you want to play the route to the right, you have to start over again. Both routes are completley different.

    1. Point One: Apparently, making a driving level is quite a lot of work for very little gameplay. So mappers tend to avoid that if possible.

      Point Two: Sounds fun.

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