Our next examples are those which can be interacted with in some way. For our first example we shall look at the humble doorway in games.
As stated above, doors afford being opened and closed and yet repeatedly in games, we come across doors that do nothing but stand there. What happens when we have a high number of doors in the game and only one of them opens? Do we force the player to try every one of them?
A game which suffered from this was the ground-breaking GTA III. Here we had a vast open-world with an unimaginable number of doors, but the vast majority of them did not open - just the shops and the areas you were allowed to go into.
Surely this in itself contradicts the term "free roaming"? And yet I've observed players repeatedly going up to these doors, trying to see if there might be one that is able to be unlocked.
Two other examples of games with frustrating doorways are Max Payne and Buffy the Vampire Slayer. In the Buffy game, there is a school level with corridors of locked closed doors. However, only a few open - and the difference between them is in no way apparent. It's a matter of trial and error.
Max Payne was even worse than Buffy. Here we had a game with a high number of doorways - again many identical - but very few actually opened. The game, again, failed to clearly show to the player a clear difference between the two - an issue much more pervasive than Buffy's single level.
In these two examples, we see a very simple but extremely common issue which causes a breakdown in affordance. We have areas which the player is meant to go through but if we do not give them the visual ability to quickly identify which is which, they are consigned to simply trying out each and every door in turn. A player's patience can only last so long.
Our next type of barrier is the one which is only in place temporarily because the player is required to destroy it in order to proceed. For our example we will be looking at the fantastic Half-Life 2, Episode 1, and Episode 2.
There are certain areas of HL2 which let the player down by becoming trial-and-error sections that can often see the player trying unsuccessfully to get past certain areas. In figure 6 we see a barrier that can be destroyed. The player knows this because other barriers with identical properties were found earlier on in the game.
However, in figure 7 we now see the exact same barrier but with a piece which is unmoveable. I spent ages trying to find more breakable pieces of wood here but to no avail. My thinking was; "Well, I can break some - why can't I break the others?"
Figure 6 - Breakable piece of barrier in Half-Life 2
Figure 7 - Unbreakable piece of barrier in Half-Life 2
What has happened here is that these barriers initially gave us the affordance that they could be destroyed, but when the exact same barrier is suddenly found to be unmoveable, the consistency within the game breaks down completely.
Also, figure 8 shows us a barrier which is nearly identical in every manner but this time is completely indestructible. How is the player supposed to know this?
Figure 8 Completely unbreakable piece of barrier in Half-Life 2
There is a danger that when this happens, the player will be too frustrated by inconsistencies to want to try and experiment within the game, and we may end up in a situation whereby the player finds himself stuck - but could quickly get by if they destroyed a barricade.
How can we expect the player to know which one is destructible and which is not? They know that something like this was breakable previously, so again the player is relying on the breakable affordance of the barrier.
The next type of barrier we can often find in games are ones which are used both as a level boundary and as an in-game interactive barrier.
The best example I can think of for this is the tremendously successful and acclaimed Call of Duty 4. What we have in figure 9 is a barrier which the player can jump over. We know this because the game explicitly informs us that by pressing space it can be jumped over.
Figure 9 - Jumpable barrier in Call of Duty 4
During quiet periods in the game this is relatively easy to see, but when the player is running away from a hail of bullets and the screen is flashing red, this message becomes almost impossible to process and simple to miss altogether.
So where does this barrier fail, then? If we look at figure 10 we have what appears to be the exact same fence, but this time it is acting as the boundary to the level and the player cannot jump over it.
Figure 10 - Non-jumpable barrier in Call of Duty 4
How is the player able to differentiate between the two? As stated, it is easy for players to miss on--screen prompt, and players could find themselves in a situation where they think one action is possible, only to find that it is not. We can easily envisage a player running through an area in the game, seeing what appears to be an opportunity for cover only to end up hammering at the jump button to no avail.