A puzzle dependency chart (PDC) is a way of showing how puzzles in an adventure game depend from one another. PDCs are credited to Ron Gilbert of Monkey Island fame. You can find lots of articles about them on the Internet, and I've written my own guide, using The Dig as an example: http://dreamsofgerontius.com/2019/06/01/puzzle-dependency-charts/.

And if you want a really lengthy analysis of Beneath a Steel Sky's story and gameplay, I've published that here: http://dreamsofgerontius.com/2020/08/03/beneath-a-steel-sky-review-and-analysis/

The general idea to a PDC is that a game has locks preventing progress and keys that you need to find to open those locks. The locks could be a physical door, or a guard (such as a goat!), or an event that needs to happen. The keys could be physical keys, combinations of objects, a distraction, or saying the right thing in a conversation. Good games have a wide range of conceptually different locks and keys.

The PDC represents these locks and keys as boxes, with arrows pointing between them to illustrate the dependencies. eg to unlock door C you need to use key A and lock B together.


In the charts below, colour coding is used to represent different locks and keys. For example, BASS has a lot of bright green - this represents conversations. You're going to be talking to a lot of different people! Yellow represents inventory objects. Purple represents new locations that you unlock as the game progresses.

Although there is some back and forth between the different levels, I've split the game up into four main sections - the Top level (with the factories), the 2nd level (with the shops), the ground level (with the rich people and their clubs) and the underground (where your destiny awaits!)

I hope you enjoy tracing the paths through this game. It's interesting to see how some parts of the game are very linear, requiring you to do exactly the right things in the right order, whereas other parts are more freeform and there are a couple of different puzzles you can work on at the same time.

Personally, I find all of Revolution's games to be a bit too linear to be true classics, but the art and themes of BASS have always made it stand out in the history of adventure games.

You start the game among the clouds. Although it's possible to die in a few different ways here, I've left these options off the chart to keep it as clean as possible. Click and download for the best quality viewing.

One thing I have shown are the two different ways you can get the wrench. You can struggle with the timing/distraction puzzle right at the start, or you can go back to the recycling centre later and just pick it up when Hobbins has mysteriously disappeared. The "easy way" wrench finishes with a dead end to avoid too many overlapping lines, but it's the same wrench!

The 2nd level has all the shops and cheap living quarters. There are a couple of important characters on this level - Gallagher and the strange man outside Dr Burke's surgery - but it's not actually necessary to ever talk to them so they don't appear on the charts.

There's a huge section of puzzles where you just have to have the right conversation with the right person. It's all a bit aimless from a puzzle perspective, but allows the story to grow as you try talking to everyone about everything and try to work out why you could possible want an anchor.

Then there's the first LINCspace section. To me, these were the highlight of the game and I'm surprised to see they get a lot of hate from some reviewers. They're not difficult, but they are a conceptual leap requiring you to get used to a slightly different inventory and understand the slightly different rules of this new world. I like that. I like that the game takes some familiar things and twists them slightly to force you to think in a different way.

Ugh, ground level. This is by far the weakest section of the game, and the chart shows some of the big reasons why.

There's obviously the huge linear section in the middle but the worst thing about it is the series of unrelated events: you discover you need to talk to the gardener from Anita's message, but he shuts you down and is completely useless, basically ending the game, except for the fact that the courthouse then opens and you have a funny but pointless cutscene, and then when that finishes the band in the club have packed up and gone home (for no reason and with no hint that I've ever found) which enables you to move forward. It's really awful design.

There's another LINCspace section here. You can blind both eyes and get the tuning fork if you want, and most people probably do, but it actually makes the ending more fiddly. The full solution to the eyes puzzle is therefore left to my final chart.

This is it, the finale. It starts with a strangely dangerous section (it never made much sense to me, knowing the ending, that Foster's life can be ended in so many different ways by people and things that should be under LINC's control).

But once all the deadly rockfalls, monsters and androids are taken care of, the end is refreshingly freeform after the linearity of the ground level. There are parallel LINCspace and real world puzzles to solve, the amusing section with Ken, and then the creepy entrance into LINC's feeding pit. The exposition heavy (and not quite making sense) ending is nevertheless better than a lot of adventure games because it creates a satisfying ending for Joey who is, after all, the character we care about most!