Level Design and Difficulty Curves

By June 14, 2017Uncategorized

In the weeks following the release of Pendulum, we were invited to speak at Colchester Digital about its game design. Whilst Frazer decided to speak about the design language of the game, visual and aural, Aidan decided to take a bitesize dive into the level design of this game and the game design theory behind the difficulty curves within Pendulum.

It seems obvious to say, but its important for games to have difficulty as without it, there no challenge. The sense of achievement is dulled if the game is too easy, players haven’t overcome much of something and a game can even feel boring after the first experience. On the other hand, a game that’s too difficult can become very frustrating. If players aren’t able to feel progress or reward for playing, they’ll quit. What is the point in playing a game you can’t get anything out of?

This is one of the reasons why a balanced difficulty is very important, and subsequently making the difficulty vary as players progress. The most common way to do that is making the game easy at the start and slowly getting harder as they progress, this is called a difficulty curve.

Difficulty Curves

Pendulum’s difficulty curve

A difficulty curve should replicates the same thing, by making the game harder as they progress, but within this overall difficulty increase there are smaller difficulty increases and decreases, making the curve move wavey in reality. This is just an example of an idle difficulty curve, a target to aim for, but in reality the difficulty curve is a more nuanced.

In this example shown above, the game gets quickly difficult at 3 points, then the curve drops. The dramatic drops being the beginning of a new chapter, and the introduction of a new mechanic. As players progress through a chapter they will have just enough challenge for the game to not get too frustrating and when it would, the game drops the difficulty making it easier and giving players a sense of accomplishment as they progress. Now introducing these “curves” of difficulty can be a challenge in of itself. It needs to slowly get harder, otherwise you make spikes of difficulty which is the opposite of what we’re aiming for here. Spikes are useful for somethings but not in this example.

Chapter 1 - the pure mechanic of the game and simplest level design

Chapter 1 – the pure mechanic of the game and simplest level design.


Chapter 2 - Opacity is added to the mix as different obstacles and targets fade in and out

Chapter 2 – Opacity becomes a game mechanic as different obstacles and targets fade in and out.


Chapter 3 - in addition to the chapter 2 mechanics, now you gravity wells that draw you in and throw you off balance

Chapter 3 – In addition to the chapter 2 mechanics, now there are gravity wells that pull you towards your death.

With Pendulum, the game’s difficulty is experienced through its level design. For example, more obstacles to avoid, targets that fade in and out so theyre harder to see and gravity wells that pull you towards your death! As the player moves through the early parts of each chapter, they are introduced to new mechanics within levels with simple designs. But the game would get repetitive if all the levels were easy, so as the player progresses we mix and match the mechanics of the game and so the levels become more complex.

This balances out a bit like this:

Player experiences new mechanic or design > Player experiences slowly increasing complex design > Player experiences greatly challenging design > Player experiences new mechanic or design.

And so on as the levels loops around over and over, keeping the game fresh and challenging at the same time.

To conclude, in order for a game to stay fun over a long period of time, it needs to find a balance between simple and challenging gameplay, but without simply being staying somewhere in-between. To keep things interesting the game needs to shift between them, creating a difficulty curve.