This game review contains spoilers. Please feel free to come back after having completed the Single Player mode of Portal 2. You'll also better understand all what's commented here after having played the game thoroughly.
This is a really lengthy game review, even it will only cover the single player mode, as there are many elements to discuss alone to also embrace the cooperative mode.
This review might miss relevant things, so feel free to comment anything you believe can complete this game review to have a better picture of the game design elements in Portal 2.
I won't cover the story of the original Portal nor the one in Portal 2 but the pivotal moments. I will only mention when characters come into scene and its motivational force behind to grasp the relationship they have with the overall game design layout.
I will use the terms "Player" and "You" indistinctly not to make the text so repetitive.
That's all i think, so let's start with the game design analysis...
The game first introduces the player to the basic game controls: moving the camera, jumping, zooming in, and the x button to trigger actions. Commands to test these basic controls are given to you by a voice off while you are locked in a room. You'll immediately meet Wheatly, a robot head that will guide and help you to escape from GladOS grip (even the story will have a twist later on).
Wheatley will talk with the character to immerse the player in the game world and to create a sense of tension, an urge to escape. This feeling will be accentuated at the very start by a scripted playable cutscene where you are tranported within your suspended isolation room amongst ruined buildings until you can get out.
(i refer to playable cutscenes all moments where you retain control of the character to a certain degree while the cutscene unfolds)
You start playing test rooms and getting used to basic operations. The one that will be more recurrent throughout the game will be moving boxes and putting them over switches to open the exit door of each test room. You'll first play a simple room, and then a bigger room separated with glass walls and several boxes to make things slightly difficult. Most gamers won't be aware of that while playing, even though it's important noticing how the learning curve of difficulty principle is perfectly applied from the very beginning.
In these two rooms not only interacting with boxes and switches is introduced, but also the concept as spatial dimension.
Soon there will be a cutscene where the player is momentarily separated from Wheatley to be given a Portal gun. The player will practice the portals mechanic shooting in the next two rooms. Here it's important to notice a constant in Portal 2: each time you are introduced a new gameplay element, you'll only practice that element individually at least in one room, to be later combined with other already learned game elements. This way game designers build up more complex element combinations to create increasingly difficult puzzles.
You'll create two portals to move yourself (or a box) from one position to another that couldn't be usually reached by normal means like walking or jumping. Actually portals can be used to transport many other things, but this will be introduced in next levels...
You'll learn here that if you shoot a portal of a certain color in one location, and then shoot again a portal of the same color in another location, the first portal will disappear and only the latest will be visible (this is one of the most elemental game play elements that define Portal and all its clone games). To sum up, there can only be one portal of the same color at a time, that's a maximum of a two portals, one blue and other orange (this is important to remark, as it's the reason why the portals location will be visually signaled at all times even you are far away from them or there are walls between the player and the portals. More on this in the third paragraph below).
With the first use of the portals another gameplay concept is implicitly introduced: the teleportation from one height level to another. this is a capital concept in the game that will gradually increase in scale in the next levels.
Now that the player has the portal gun, he'll combine portals with switches and boxes in the next rooms to automate these recently acquired game mechanics.
Another important thing to notice here is the lack of interface (besides the portal gun as in almost any FPS). We could say the interface is integrated in the level design. For example, switches are connected through a dotted line next to the exit door. When they are off are represented in blue color, and the end of the dotted line displays a cross to indicate the exit door is closed. When a box is put over the switch, the dotted line changes to yellow color and a ticked signal is displayed near the door to indicate it's open.
This visual hep will be vital in advanced levels to figure out things when rooms are bigger and intertwine much more interactive elements.
Notice here that portals will be still visible (with a clearer color) once they are out of the character's sight (for example, hidden by a wall). This way, the player can know at all times where's the portal he shot and what color it is. As you can indistinctly shoot a blue or orange portal no matter the order, many times you'll find yourself thinking what portal you shot first so you don't have to go back to create the portal again, so this visual help is much necessary to avoid a feeling of frustration.
Probably many players have suffered some momentary amnesia regarding what color portal they shot first. Game designers must have thought deeply about this issue, but the option of momentarily deactivating a portal button that has already been shot would have not worked without seriously affecting the game design flow, as there are puzzles where the player is required to shoot portals very quickly to progress further. Such decision would have made shooting portals something too restrictive.
There are many things to talk about yet (and more interesting i dare say!), so i think there will be 4 or 5 more parts like this one in coming days. Now we better take a break with your permit to assimilate all what we've talked about. =)
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