Portal 2 developer commentary: Difference between revisions

=== Big Door ===

| The size of the gigantic transition seal lock was a happy accident. We knew the connection between old Aperture and new Aperture had to be a big set piece. The first model built was about five times bigger than everyone expected, but people started to like it.  We joked that it should be a bullet point on the Portal 2 box: "Features the biggest door in games ever!"  We decided it would be fun to play with the player's expectations and put a puny looking door behind it, along with a few small props.

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=== Janitor Bob ===

| We had to come up with old-looking versions for all the important gameplay props, such as button panels, doors, cubes - basically everything the player could interact with. We came up with this fictional character - Janitor Bob. He'd be the guy who had to maintain all of old Aperture. A guy who doesn't understand anything about science but can fix everything with duct tape and a screwdriver. He would use everything he could get his hands on. The result might not look pretty but it would work. So whenever we got stuck designing props for chapter 3 we'd ask ourselves: "Well, how would Bob build it?"

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=== Elevator Fatigue ===

| We found that playtesters were getting fatigued at solving so many complex test chambers in a row. So, instead of a routine elevator ride to the next puzzle, we added a long funnel ride with some destruction to give players a short break while reminding them of the facility's state of disrepair.

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=== Reference Materials ===

| While making Portal 2, we explored our way through vast quantities of reference material. Inspirations included photos of NASA’s Apollo and Shuttle programs, CERN’s particle accelerators both modern and obsolete, industrial robots, derelict Soviet space shuttles, overgrown temples, Brussels metro stations, seedy American motels, junkyards filled with rocketry equipment, Chinese apartment blocks under construction, Polish shipyards, neutrino detectors deep underground in nickel mines, corporate headquarters from a variety of eras, commercial nuclear reactors, experimental fusion reactors, rain-sodden book depositories in Detroit, peculiar cameras, forgotten space probes, you name it.

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=== Kill Your Television ===

| In each of Wheatley's test chambers there is always a monitor with Wheatley on it. While placing the monitor in this level, one of our designers thought it would be funny if the monitor was the target of the faith plate and would get broken if the player or the box flew into it. We thought the gag worked well and decided to make every monitor breakable.

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=== Nonlinear Progression ===

| The original layout of this chamber started out much more linear; essentially a sequence of rooms that the player had to progress through somewhat blindly – not knowing what the next goal might be until they got there.  Early versions contained an extra puzzle beyond the reflector cube, but due to the linear path, it took players so long to get to it, that they were confused about which elements were still relevant. This drove us to make the level nonlinear.  To make it easier for players to visualize the puzzle, we condensed the overall test space and moved the exit near the start. This helped the players see where they had to go and which objects would help them get there.

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=== Blobulator ===

| The first implementation of the blob was integrated in the Source engine back in 2007. Over the years, the code has been significantly optimized, but was still way too slow to run on game consoles. The blob was a key feature of Portal 2, even though we did not know if we could make it work for consoles. In summer 2010, we were still considering using a completely different tech for consoles--one that would certainly not look as nice. On the 360, even with a very low quality blob, we were barely within our performance budget. But we really wanted to have the same high quality blob among all platforms. Meanwhile, the code was poorly suited for PS3 SPU. We ended up re-writing all the blob code so it would take better advantage of multiple cores and SPUs, giving us quality blobs on all platforms while staying within performance and memory constraints.

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=== Horrible Accents ===

| The breakout sequence here was originally a lot longer, involving Wheatley talking to you in a horrible American accent, assuming GLaDOS can't hear him. Simultaneously, we'd have GLaDOS commenting on the entire ridiculous exchange, because of course she can hear him. When we playtested the concept, every player made a beeline for the opening. So we either had to ditch all the dialogue or figure out a reason for the player to stand around for five minutes even though they could escape at any time. We ditched the dialogue.

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=== Caroline ===

| The character of 'Caroline' came about because we wanted somebody for Cave to play off of.  Though we had originally envisioned a put-upon Scientist character called Greg, it would have been wasteful to hire an actor for just one or two lines.  Instead, we hit upon the idea of economizing by using GLaDOS-actor Ellen McLain.  Out of nowhere, we suddenly had an opportunity for a GLaDOS origin story.

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=== Potatos ===

| The character of PotatOS was actually the hardest one to crack for us, and was the last character to get recorded. We’d always wanted to switch things up for the sequel, so that GLaDOS would become your unwilling buddy cop partner against a new threat, but this ended up being far more entertaining as a concept than in execution. It’s one thing to have an omnipotent villain chastising you while you’re testing. It’s quite another to have a little potato on your gun doing the same. Playtesters wanted to tear her off the gun, and we didn’t blame them. So we were faced with the unsettling prospect of making dry, robotic supervillain GLaDOS more human and relatable. This ended up being one of the hardest writing jobs in the game.

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=== Birdbrain ===

| One of the larger plot holes that PotatOS introduced was: She’s your buddy now. She’s got the same goals as you. So why isn’t she helping you solve the tests? The real answer is, obviously, that if she did help you solve the tests there’d be no game. One solution we we came up with was for the bird from Act 3 to keep swooping in and pecking bits of her off your gun. As the bird kept eating the part of her that knew how to solve the tests, PotatOS would actually get dumber over time. For technical reasons, this ended up being impossible to execute, so we ended up finding another solution. Some of us though will always have a place in our heart for the bird solution.

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=== Evil Wheatley ===

| Finding the right balance for Evil Wheatley was difficult, because we still wanted him to be the bumbling idiot from the first half of the game, but at the same time, there had to be some sense that he was dangerous now, otherwise there wasn't much tension for the big finale. Fortunately, Stephen Merchant did a great job of intercutting funny bumbling Wheatley with occasional outbursts of power-mad, villainous Wheatley.

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=== Decorating Aperture ===

| This chapter gave us a great opportunity for visually telling the backstory of Aperture Science. We accomplished this with signs, props and materials. In this area, we get a glimpse of what Aperture Science must have been like in its heyday. We used rich, warm colors and materials like carpeting and marble to indicate that Aperture had a lot of money at one time. Cave Johnson and his staff were just starting out in their enterprise and everyone was eager to do science. This stands in contrast to the stark, cavernous environment outside and the materials you see in the Aperture Labs from later decades. As the player makes their way through more recent areas of the lab, the materials become cheaper, with an abundance of plastic and linoleum showing that Aperture had fallen on harder times and could no longer build high-quality offices for its workers.

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=== New Sounds And Old ===

| The newer and older versions of Aperture show their distinct personalities in sound as well as visuals. The doors, floors and buttons, as well as soundscapes, reflect the aging, outdated 70’s feel. The sounds contain hints of the decaying metal and wood. The newer but unstable Wheatley chamber soundscapes become more foreboding and perilous the further you venture into them. The atmosphere of uncontrolled destruction continues to intensify till the end.

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=== Gel Sounds ===

| With the gel sounds for Portal 2 we wanted to create something whimsical that would add to the player’s enjoyment of the mechanics, without crossing over the line into ludicrousness.  For example, our initial pass at the blue gel 'bounce' sound included a rubber playground ball, a pitch-bent harp string and a processed mouth harp.  The resulting sound captured the idea of fun, but was off the charts on the goofy scale.  After several iterations we settled on the current, less over-the-top sound which features a piece of metal bar bouncing like a diving board and a heavy dose of synthesis.  It’s not as wacky, but hopefully it’s still fun.

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=== Turret Building Machine ===

| We felt that most players of Portal, ourselves included, wanted more opportunities to look behind the scenes of Aperture--and not only into deserted crawlspaces, but into the vital heart of the factory.  The turret factory was a way for us to satisfy this desire, while also answering the nagging question of where all the stuff in the facility came from.  Because we constantly allude to the turret creation process throughout the game, it is satisfying from a story standpoint, to finally stand before the machine you've been hearing about.  By showing how turrets are made, it's easy enough to extrapolate a similar creation path for all the other items that Aperture generates only to be consumed by the endless process of product testing.  We designed an entire life cycle for the poor doomed turrets, from creation, product testing, error detection, packaging, and their ultimate unpackaging prior to being recycled.  In fact, the turrets never make it to shipping.  As soon as a turret is completely finished and packed in a box, it is immediately sent to the un-boxer, where it goes on to recycling and begins its life anew.  Thus we show Aperture continually building and repurposing its items in the most inefficient way imaginable.  We never got around to building the actual unboxer, but what we pictured was that it was located immediately below the boxing machine.  And while the turrets would be reduced to their components, the boxes would be discarded and end up in a steadily growing mountain of unrecycled packing materials.

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=== Frankenturrets ===

| The Frankenturrets were an attempt to show one of the ways Wheatley has been spending his time since he threw the player down into the Underground. Using his limited brain, it didn't seem like he could have come up with a lot, so the idea of using objects he'd have access to seemed appropriate. The turret and the cube are the two most iconic portal objects and the frankenturret is little more than a crude combination of those two objects.  The hermit crab animation when you pick the cubes up began as a necessity because we really needed to make them act like cubes when you held them. It ended up being so cute that it became a simple job of making the turret widen its eye and shake its head a little, to convey to the player that these things were disrupted, and had no idea who or what they were anymore, and also to make the player feel sympathetic towards their plight. We used a combination of  in game physics pushes and canned Maya animation to allow the player freedom to move them wherever they wanted, line up races between them, or even set them up so they would walk, inevitably to their doom, into a fizzler.

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=== Vacuum Transport ===

| Vacuum pipes cropped up occasionally in the original Portal, but this time we wanted to show that this was the main way that Aperture transported all of its supplies about the facility. It felt very true to Aperture, in that it seemed like an inefficient and ridiculously expensive solution to their transport problems. We also wanted it to feel more violent and physical than before, with objects constantly ricocheting against the sides of the pipes.  It was as if Aperture had no real control over the system, and no real care for the things they were transporting. After all, they have thousands of the things.

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=== Stalemate ===

| The stalemate resolution button is the earliest configuration of the robot arms we tried. Playtesters enjoyed it, but it took us a long time to find the right place for it in the game. It clearly needed to be defending something, and for a while it defended a paranoid personality sphere who had built a huge encampment of defenses to stop you from getting to him. When the idea for the stalemate button came up, we knew it had finally found its home as part of GLaDOS's last desperate attempt at self-preservation.

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=== Tag: The Power of Paint ===

| Similar to the way the student game Narbacular Drop became the original Portal, the paint mechanics in Portal 2 come from a student game,  Tag: The Power of Paint.  The repulsion gel in Portal 2 is modeled after the bounce paint from Tag, but was redesigned to fit better within Portal.  The original bounce paint always bounced the player at a fixed height and activated whenever the player touched the paint.  We changed the repulsion gel to reflect the player's velocity, such that they will bounce back up to the height that they fell from.  This mechanic lends itself better to puzzles involving portals because players have to think about gaining and preserving height.  We also changed the repulsion gel to only activate if the player jumps off of, or falls on to the gel.  This was done because players would often accidently walk onto repulsion gel they didn't see and then trigger an unwanted bounce.  This was a particularly nasty problem in Portal 2 because the player couldn't get rid of paint once it was applied; whereas in Tag the player can erase paint at any time they want.

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=== Porting Paint ===

| While re-implementing the paint mechanics from our student game, Tag: The Power of Paint, in the context of Portal 2, the biggest change we made was to exclude the paint gun. In Tag, our paint gun allowed the player to paint the environment freely in an abstract outdoor environment, but in our gameplay experiments, that was very difficult to constrain without contrivance in Portal 2's indoor spaces. It also changed the game's pacing significantly, since being able to run at high speed around a level covering everything in paint is lot more fast paced, energetic, and often scattershot than Portal's more cerebral gameplay. Perhaps most importantly, there's a certain elegance in the simplicity of manipulating all the game elements using only the portal gun. Adding a new gun would inherently add complexity and force us to start from square one training the player how to use this new tool, instead of focusing on the game's namesake. Instead, we decided to use the established mechanism of the delivery tubes and have players redirect the flow of the paint with their portal guns. This felt like a good compromise.

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=== Speed Paint ===

| Propulsion gel carried over almost exactly the same as the speed paint in the student game, Tag: The Power of Paint, except that it is slightly more than twice as fast. Propulsion gel combined well with the existing mechanics of Portal, such as flinging, and it also went well with the repulsion gel for long jumps. We had to tweak the player's control on propulsion gel to feel right in the Portal universe, and also added a slight funneling effect to help guide the player when they are speeding into a portal.

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=== Crazy Box ===

| One of the things that the student game Tag: The Power of Paint didn't allow was painting of other objects, since this would have been too trivial in that game.  In Portal 2, however, moving paint around became a puzzle in and of itself, so we began to create puzzles that depended on painting objects. Bouncy boxes and turrets were an obvious choice, and adding this mechanic extended our toolbox to include objects whose basic properties of movement could be changed by the player.

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=== Portal Paint ===

| Portal paint was the last paint we added to the game, and for a long time we weren’t sure of the best way to use it. We experimented with the delivery method and found that it was most effective when it was deployed in large quantities.  Another important factor was the angle of application. Dropping the paint at an angle allowed the player to play more freely with the paint, which gave them the liberating feeling of breaking the rules by being able to place portals where they couldn’t before.

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=== The Ascent ===

| The lake map marks a total reset to the aesthetics and scale of the environments up to this point in the game. You come into the underground cave compressed and as you progress further into the map, your eye is drawn upwards by the elevator tower, sparking cables, falling debris, and finally the test spheres which recede vertically into nothingness. This looking upwards gives the player sense of the vastness of Aperture before GLaDOS and a visual sense of the daunting climb they will have to make to get back to Wheatley. The open areas encourage the player to explore their surroundings and take a break from the intensive puzzle solving of the test chambers.

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=== Wheatley's As Level Designer ===

| Wheatley's first test was really fun to make because we wanted it to feel like he was a first-time level designer. We see a lot of maps where people try using different textures or lights to write words or put their names on the walls.

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=== WheatDOS ===

| Our initial idea for this version of Wheatley was to replace GLaDOS's eye with Wheatley's, but it wasn't a big enough change to see the difference. Instead we put Wheatley onto GLaDOS's rig, and gave him a puffed out look, like he's trying to make himself look big, using wall tiles.

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