Category Archives: game design

Although in general I’m pretty happy with the design of Production Line, its clear that there are some issues with the way research is implemented in the game. Something I really like is the idea of a BIG tech tree, and players making decision as where to concentrate their resources in terms of competitive advantage. For example, you may focus on production efficiency, or maybe on product range, or maybe on costs, or on high-technology to making high-end cutting edge cars. Different strategies should work.

The trouble is, despite the big tech tree and different approaches, the research-choice decision (which should always be *interesting* as every decision in a decent strategy game needs to be), tends towards more of a nuisance in the late game than a joy. The reason is that research seems to get quicker and quicker, and the costs of doing it become trivial.

At the start of the game, I really need the player to be able to buy some research facilities, otherwise they cannot progress. The problem is, as we go from a tiny little factory to a big one, the cost of ‘one more facility’ becomes relatively trivial. Of course, I can make later techs more expensive in points to research, but you can’t go ‘too far’ in that direction without it automatically herding the player towards doing ‘lvl 1′ techs first and removing that initial flexibility. The flip-side is that if you *not* scale the tech costs, then later in the game, someone who has ignored a specific branch of the tree can normally just go click click click’ and research it in seconds. again: unsatisfying.

FWIW I note factorio has this problem to some extent too, although generally it works better overall because the mechanics of research there are way more involved, rendering the ‘cost’ of the facilities fairly minor compared to the manufacturing of tech ingredients.

Anyway, how do I achieve the following in my design?

  1. Make tech tree choice interesting from the start, with multiple paths accessible.
  2. Allow tech to continue to be researchable at a reasonable, but not annoying rate.
  3. Prevent tech-spamming where the research cost becomes moot.

I’ve mulled over a lot of possibilities. here are some solutions that I have considered, either together or separately:

  1. Have hard caps on the number of research facilities that can be built before some other (expensive) admin tech unlocks ‘advanced’ research, thus putting the brakes on research in the mid-game
  2. Have variable costs to run or buy research (probably let scientist wages rise as more are hired), making research spamming non-viable in the late-game.
  3. Allow research queueing, so that the player can ignore research for longer periods. (Not ideal, as each research SHOULD be a catalyst for production line and car model re-evaluation).
  4. Have different ‘types’ of research require purpose built facilities. Maybe design-related research requires dedicated design studios? Maybe super-high tech research requires very expensive dedicated and large labs?
  5. Reduce or prevent the immediate construction of any research facility, but require a construction or hiring people for staff. Maybe placing a research facility means it takes 3-4 hours before the staff can be located to fill the facility and start work?
  6. Maybe introduce licenses, or patents that act as gatekeepers for research. To research reversing cameras perhaps you need to license a patent for it ($400,000) AND then research it once you have put that money down.

The problem with 1) is it seems very ‘gamey’ and arbitrary, and not intuitive for the player to understand. 2) sounds like it would actually make sense, although I need a decent way of letting the player know about the changes. 3) seems a quality of life improvement in general, but its also treating the symptom (research-popups are annoying) rather than the true cause (research happens too quickly in the late game, and does not seem to have enough of an impact to demand attention.

4) is interesting, and certainly one I’m attracted to. I like the idea of having to place down a design-studio facility, and to effectively research car designs entirely separately. I like the idea of a purely ‘design’ based arm of research for stuff like interior styling changes, new paint colors and types, and so-on. It also seems unlikely that someone who helps design the tire-making press is also working on voice-recognition software.

5) Sounds like its acceptable because build times for facilities are quite common in games, but then how do I justify the fact that everything else in the game is placed down instantly?

6) Could be interesting, and probably plays into a wider revamp of the research system where I need research-pre-requisites not to be limited just to other research items.

I need to get this right, so I don’t want to rush into a solution. I also feel this post is way too designy, I haven’t even tried to pimp the game. QUICK! Add a steam widget!

The hardest part of game design for Production Line has been the sales model. Not hard as in technically hard (frankly after 36 years of coding, not much is *technically* hard), but hard as in balancing the various needs.

The current system for selling cars in production Line works like this:

Each feature in a car has a ‘base value’, which is essentially derived from the resources and time/power/research required to make that component, plus a normal profit margin. That gives a value of say $100 for the feature, and if we include that feature in our car, we will get $100 for it when it sells, assuming we sell cars at a ‘normal’ rate.

If we are wildly profitable, more companies will enter the market and put general downwards pressure on prices, squeezing the profit margin thats considered normal, and forcing us to reduce prices. The reverse is also true.

The value of a feature decreases inversely with its ‘rarity’ as more and more competitors make that feature available. Some features (most) can eventually be considered ‘universal’. There is a multiplier applied to the final value of each feature based on how rare or common it is.

Finally, ‘customers’ appear on a regular basis and shop for cars. They have a probability based approach to buying. So a cheap car is likely to sell immediately, an expensive one will get passed over again and again until eventually a customer buys it.

So that is the current system as it stands, in build 1.22 of the game. Its not bad, it achieves a lot of my objectives. Competition acts a a balancing factor, research is incentivised, and mass market production means you need to lower your prices to compete. However, its not perfect because it assumes that basically there is just one model of car and one type of customer. This needs to be fixed.

My current thinking is that I need to reflect a number of new characteristics in the model:

  • Demand for your cars need to be scalable with marketing (not implemented yet)
  • There needs to be different overall demand for each body type (sedan, compact, SUV etc), which I can control with events.
  • The ‘rarity’ of features needs to be associated with final price. Everyone expects sat-nav in a $50k car. Not so much in a $10k car…
  • All of these factors need to be clearly presented to the player so that they understand how the market is working and WHY cars are selling or not selling.

So in other words, if our car showroom has a dozen SUVS where we set a 20% price premium, all of which have the rare and modern climate control, but none of which have electric windows, and competition from other car makers is currently extremely high, we need all of that to be displayed in a way that shows the player why its taking so long to shift those SUVs, and what they can do about it. The current system does none of this.

Also, because the game is in early access, I can’t just take months off to faff around, I need to make steady progress on this stuff. So with that in mind:

The current sales(showroom) GUI does nothing to show the level of price competition with other car manufacturers. This is already in the game, but not being shown. Maybe a pie chart or bar chart showing our current market share would be a good indicator to add to the showroom?

The number of customers who visit the car showroom that do (or do not) buy a car is also currently modelled but not shown. I should probably get some GUI added to reflect this, even if its just (for now) a percentage indicator showing the number of people who did/did not buy a car. (Plus I could also show the average length of time each car was on the showroom floor?

Once that is in the game, I can start thinking about modelling those per-body-style markets. This could be a multiplier that reflects the needs of each customer, so instead of being open-minded, they could now be SUV buyers or Sedan Buyers. This would allow me to show a breakdown of the visits to the showroom by each customer, and also breakdown showroom-times and sales percentages for each body style (or each car model) in an additional stats tab in the showroom window?

And then phase III would be modelling the different expectations of features on a car-price based model (electric windows expected on cars above price $X…). That would require a fair bit of internal code wrangling PLUS some fancy GUI changes.

Anyway, I’m interested to hear peoples views on all this, does this sound like its going in the right direction?



So, when watching a lets play for my new game Production Line, I encountered the point that ‘surely compact cars should sell for less than an SUV? given the same options…?’ Which is of course absolutely true. As a result I immediately leapt into my code and made it so. There is now a price modifier for each body style, with compact cars being cheaper, sedan being the default and SUV being more expensive. So far…so good.

But in the current game, producing all 3 cars takes the same time and resources, so why would anybody ever build a compact car? Suddenly I have introduced yet another dodgy piece of game balance. Argggh. In the back of my mind, I have always planned to simulate multiple ‘markets’ for cars (sop one sort of customer is looking for a compact car, another for an SUV etc), so the strategy of purely producing SUVs would be a bad one, but there still remains the problem that I have hard coded higher profitability into the larger vehicles. Plus this means that because it only applies to the base car features (wheels, doors, roof etc), there is an additional incentive to sell ‘basic’ SUVS, whereas we all know that cars make a lot more profit on the extras…

So to quote Tolstoy, ‘what is to be done’?

The obvious solution here would be to reflect the extra effort in building a bigger (or smaller) vehicle in the game mechanics, and have everything balance out. Presumably making a door for an SUV is harder work and more expensive than making one for a mini. Also in theory I guess you need bigger stronger robots exerting more power to lift heavier doors, yada yada. The amount of steel in the roof of an SUV is likely noticeably bigger than for a compact car, and so on.

The trouble is, I have boxed myself into a design corner in my game by making resource units ‘discrete’ (ie: not fractional). Components use up ‘1’ steel or maybe ‘2’ steel, but never ‘1.2’ steel. To change this would not only be a huge endeavour, I suspect it would lead to confusion, as individual items of resources are represented graphically and fall into neat slots. As a result of this, pretty fixed, design decision, I don’t think realistically I can change the resource quantities needed to make different car body types.

So the alternative that presents itself is to instead vary the time taken to assemble them, which is fractional, and could be relatively easily adjusted. A set of robots at the ‘fit doors’ slot could easily take 20% more time on an SUV than a sedan. I could probably code that in 30 minutes. The only problem there is how to represent that to the player. The window that shows the slot status for something like this does show how long the task will take, but there is no further breakdown. Hovering the cursor over some upgrades will tell you how much time they have added or subtracted to the total, but that involves some maths by the player to work out the ‘base’ process time.

Maybe this is something I just have to accept, and possibly just provide a little ‘i’ icon to hover over which shows a breakdown saying that the task takes 2 minutes 10 seconds, plus 2.3 seconds because we are fitting an alarm as well, minus 1.2 seconds because its a compact car, – 0.65 seconds because we have extra robots…etc…

Too clunky? or a reasonable compromise? I haven’t decided yet.

Something that is much requested, and that I am also keen on (and currently working on), is different body styles for Production Line. Currently there is just one body style: the sedan. It has optional spoiler and aerial, and a bunch of colors, but otherwise thats it. Obviously we need SUVs and compacts and sports cars and pick-up trucks and many more (I held a poll, and SUV and compact won).

Deciding that new bodystyles need to go in, and will go in, is easy. The tricky thing is how to implement it within the game.

I’ve mused on this for a while now. My initial plan was to keep things simple. Forcing the player to have completely separate production lines for each vehicle might make sense in the real world, but I think it would be pretty annoying for the player. On the other hand, some players may want to do precisely this, and feel that not doing so is ‘cheating’. We all know that factories tend to produce just 1 model, and that the same robot/person does not screw the same headlight onto an SUV or a compact car.

Actually the main problem is that if we *do* have different production lines, that also means we start needing new resources (if we follow that train of thought). So suddenly we don’t have sunroof, we have sedan sunroof, compact sunroof, SUV sunroof…etc, and the complexity starts getting ridiculous. As a result, I want to have a compromise situation where there is reason for the player to organize his production lines into separate bodystyles, but not enough realism to force them to worry about 6 different types of trunk or 6 different headlight types. There is complexity that leads to interesting and fun gameplay, and then there is just annoying busywork… I *could* allow component re-use across body styles but never allow lines to cross or meet, but then does it become more like tetris and less like a business sim? and do I now need a lot more export slots? Plus the routing code would become even more like spaghetti.

So I think I’m going to say that a ‘sunroof’ is a ‘sunroof’, and it can be fitted to any car. Obviously the final visual effect ‘on the car’ will be different, but I’m not going to force the player to micromanage different types. Obviously this isn’t totally realistic, but then sexy elf boob-armor and men carrying guns six times their weight isn’t either so throw me a damn bone here ok?

My compromise back in the land of realism is this:

Because allowing components to be interchangeable, and therefore allowing fitting slots to be interchangeable between body styles *could* lead to the weird sight of a jumble of different cars all trundling along a production line, which feels *wrong*, I’ve decided to allow this… BUT…. *drumroll* …. have a ‘re-tooling’ penalty in time whenever the bodystyle changes for a slot. In other words, when you weld the doors on an SUV, and the next car to rock-up to your slot is a sedan, you have to wait X seconds (probably some multiple of the normal work time) to realign your welding widgets, or whatever. This *allows* for bodystyle changes and thus mixed-production, but penalizes excessive swapping.

I think that’s quite a neat compromise, especially because I can then allow you to research ‘rapid re-tooling’ to lessen the impact. I actually already have tech named ‘retooling’, which I can rename to ‘asset recovery’ as that’s more accurately what it does.

Anyway, that is my current plan. When multiple body styles are researched, the player will be able to select from a drop down list at the start of the line which body style each new vehicle uses, and that carries through its entire life. Obviously it will need more tweaking at the business side of things, and also I would liked to find a way to ensure that SUVs cost more (for example), but I think its best to get multiple car styles in there sooner rather than later as its clearly something people want to see in their factories.

I do have plans for proper design studios and clay car models, but they will likely come later, if people want them.

In other news I’m working on early access readiness for steam. GoG will come too. I have to get a video named (its in progress) and I’m getting proper music too. Busy busy busy. it looks like new car types are likely to be the last new thing (apart from polish and bug fixes) that goes in before we go into early access.


When I initially designed the Production Line ‘car design’ system it sounded like it made so much sense. Cars were a list of ‘features’ such as ‘electric windows’ etc, and whenever a car came to be sold, we would see if we had sold a car with that list of features before or not, and if not, we popped up a dialog box asking the player what to call this design and how much to charge with it, along with information on the market value (fair price) for that combination of features. This seemed perfectly reasonable.

The problem is that a) there are about 999,999,999 permutations of features and b)actual cars arent really sold that way anyway.

If you buy a car, you decide to buy (for example) a Vauxhall Astra, and then you decide which options you want, effectively from a price-list of add-ons. Usually car companies bundle a set of features together as certain ‘models’ such as ‘deluxe’ or ‘GT’ or whatever, but essentially there is a base body design and a price list of features to go on top. In order to reduce the amount of pointless GUI and busywork in Production Line I decided to switch to a similar model for patch 1.13.

Now we have a new button in the GUI, which launches the ‘design browser’ in the game which shows you all of the actual properly different body types of cars you currently produce. (for now its hacked showing designs from an earlier version, so they all have the same body type, but for new games you will only have one here for now). That window lets you select which car design you want to view or edit.

That then brings up this new window, which will also pop-up when you produce a car for the first time, or when you ship a car with a feature that was not previously available in this design. (That should happen only when you have researched a new upgrade and then shipped an upgraded car).

This is where the GUI gets a bit confusing. Essentially any design is just a shopping list of features with the base feature being ‘basic car’. For each feature you can see the market value of that feature (the consensus in the market place for the fair value for one of those), the price you are currently charging, and the markup over the market value in both percentage and dollar terms (with buttons to adjust this).

You can price cars at a premium to earn higher profits, or a discount to shift them quicker. This is where the confusion will come..

This does not represent a hard profit or loss for that car.

because there are so many fixed costs, its very very hard to work out how much each feature really costs you to add, so you have to separately keep an eye on what that feature is costing you. The premium/discounts here are only a guide as to how competitive you are with your rivals, who may be more or less efficient than you. My big dilemma here is how confusing is this? and is there a better way to explain/present it? Obviously there will eventually be a tutorial.

I also think that probably what I need here is some option to copy a single premium/discount to all features, so you are not adjusting each one manually. I’m not sure of the best way to present that from a GUI POV. In terms of ‘why would you ever not want to do that?’ consider this: You rush ahead in the early stages of the game to research cruise control before anybody else. As a result, you have the ONLY cars with cruise control. You can therefore charge a whacking great premium for that feature, way above the premium you would charge for other car features.

Does that make sense? Is this an improvement on the old model? Feedback most welcome. This is hopefully going into the 1.13 patch coming this week. maybe even Wednesday! (more likely Thursday).

BTW don’t forget the price goes to $12 from Sunday. If you know you are going to get it anyway, order it below :D