I haven't really studied game design much, but seeing as I want to make games, I figured I had better at least pay attention to the games I play and see what I can learn from their design. I've learned a lot of things about game design and a lot of things about myself - namely, I like puzzle games, and there's a trend in puzzle games that makes them more fun for me.

I've recently been playing a lot of Portal. A lot. I've played Portal 1, Portal 2, Portal Stories: Mel, Aperture Tag, Rexaura, and many, many community maps for Portal 2. (Though I have not played anywhere near as much as this guy). One thing I have noticed consistently is that I enjoy fizzler puzzles - you know, those ones where one or more Aperture Science Material Emancipation Grills play a crucial role in the puzzle?

A fizzler in Portal 2, with a nearby cube to show the effect.
Fizzlers in Portal 2 allow you to pass through them, but they impose certain limitations. You cannot shoot portals through them, and when you pass through them your existing portals are cleared. Also, any objects that come into contact with them are fizzled - that is, destroyed. However, lasers, light bridges, and excursion funnels can all pass through them without issue. From a simple standpoint, this makes them a sort of special kind of wall that you can only pass through if you are willing to lose your portals and any carried objects. However, there is a bit more to them than that - for you see, they can also be turned on or off.

If you can, you should play The Winter Testing Initiative - the last puzzle is a fizzler puzzle and had me stumped until I looked up a walkthrough. Fizzler puzzles become very challenging when you can turn off the fizzler temporarily - you suddenly have to think far more carefully about when and why you would turn it off, because when you turn it off you can shoot portals on both sides, but then you may be required to turn the fizzler back on. Suddenly, you have to keep your portals on each side of the fizzler and never touch the fizzler. You also have to decide which side of the fizzler you want objects on. It introduces a whole new level of challenge despite the rules being so simple.

The Portal trilogy aren't the only games with this concept, though; Antichamber, another of my all time favorite games, also employs fizzlers - a few different kinds, actually. Some fizzlers don't let you carry bricks through in your brick tool, but you can shoot bricks through them and move them to the other side. Other fizzlers will let you carry bricks but won't let bricks exist within them, destroying them on contact. There are also fizzlers that do both. Several puzzles in the game revolve around outwitting the fizzlers.

A fizzler in Antichamber.
Another game, The Swapper, also features fizzlers - there are fizzlers that clear your clones when you pass through them (which are only used for story purposes and never as puzzle elements, unfortunately), but there are also red and blue light sources which block swapping and clone creation, respectively. When red and blue light overlap, it creates purple light that blocks both. Nearly every puzzle in the game uses these lights to prevent you from taking the obvious approach - in fact, the game would not work without them. The lights are also often turned on or off by switches, and the light sources themselves can even be blocked by physical objects.

A fizzler (left) and colored lights (center) in The Swapper.
Even The Witness has something a little similar - what I like to call "strategic breaks". The line puzzles in the game often have breaks in the grid that prevent the line from passing that way, forcing you to use a different path. I often found that these breaks were placed in such a way so as to block all the obvious and trivial solutions, forcing me to get creative and think outside the box.

A puzzle in The Witness with two "strategic breaks".
So what is it about fizzlers that makes puzzle games so much more fun and challenging, aside from the fact that the English spellings of the words both have the double Z? Well, I think it has everything to do with constricting movement in a logical manner. Fizzlers force you to act in a certain way that no other puzzle element does. Sure, a wall will block your path, and a light bridge is only so wide, but fizzlers can be turned off and they have special rules about what they allow through. They require far more strategic thinking - can I walk through this fizzler and reset my portals? Do I need the cube on this side or the other side? Can I shoot bricks under or above this fizzler and access them on the other side? Can I create a clone on the other side of the light and then switch to it after pressing this button? Can I draw my line this way and satisfy the requirements like that instead?

Fizzlers require thinking about alternative solutions. They aren't always wall, because the player might be able to pass through them effortlessly. They aren't always door, because you might be able to walk through them whether they are on or off. They generally aren't deadly, though Portal 2 does have deadly player fizzlers. They don't have to be moved from point A to point B. They don't have to be stood on to satisfy a requirement. They might not even have on and off states.

The interesting thing about fizzlers is that they can be found even in games which are not primarily puzzle games. Think force fields which allow passage but cannot be shot through. Sci-fi shooters are full of them. Sometimes they are even just invisible walls to prevent objects from leaving areas. However, despite the fact that you can find a fizzler in so many games, very few actually take advantage of their properties - generally fizzlers are just used to prevent the player from doing something that the developer doesn't want them to do. Things get interesting when developers use them to force the player to do something they want the player to do.

A picture I might have copypasted from the internet.
The Legend Of Zelda: Twilight Princess has a very interesting mechanic in one of its dungeons. You are required to carry around cannonballs so that you can place them into cannons and destroy obstacles (walls, enemies). However, Link cannot carry cannonballs through doors - you have to set down the cannonball before traversing the door. Sounding familiar? Additionally, next to certain doors are devices in which you can place a cannonball and then retrieve it in the other room. Yes, I am saying that fizzlers exist in the Zelda universe too, they are just cleverly hidden in a puzzle mechanic. Or, rather, they are the puzzle mechanic.

My point is, whether fizzlers are obvious or not, you can usually find them in good games, and for me the most challenging and engaging games are the ones that take advantage of their properties. But what do I mean when I talk about fizzler in the general sense? In Portal, fizzlers are a field that disintegrates objects and resets portals. In Antichamber it is much the same. The Swapper is where things get interesting - not only is there a traditional fizzler that resets your clones, there are the colored lights that I also consider fizzlers, just a different kind. The colored lights in The Swapper don't disintegrate objects or clones, but they do prevent using your abilities in certain areas. Where you cannot shoot a portal through a fizzler in Portal 2, you cannot swap to a clone through red light in The Swapper.

What about The Witness? Surely I don't consider the strategic breaks to be fizzlers too? There are no objects to be destroyed, no guns to shoot, no switches to toggle them on or off. Well, you're right - I don't consider them to be fizzlers. I threw them in as a red herring - they are just plain ordinary walls. Basically, I lied to you in order to get my point across. Will you accept my apology? Yes? Good. Now let's talk about my general definition of a fizzler.

To me, a fizzler is any selective filter in a puzzle game - it must allow travel for some things but not others. Things that can be filtered by a fizzler include the player, various objects, and remote abilities (such as portals as in Portal, energy orbs as in The Turing Test, or bricks in Antichamber). This definition supports fizzlers in Portal, Antichamber, The Swapper, Twilight Princess, and The Turing Test.

That's it! We have a definition. Are there any other games which contain fizzlers by that definition, obvious or not? Let me know! Or don't. That's fine too.

UPDATE 2016-07-20: I've played more puzzle games and found more fizzlers! It's almost as if there is a correlation...
In "The Talos Principle": a classic fizzler (left) and a toggleable barrier (right)
In "Red Trigger": a basic fizzler that resets your blocks and energy when you pass through it, but you can also shoot through it