Archive for December, 2009

James Cameron's Avatar Promotional Image
Immersive setting, great computer animation, classic high adventure story… it’s like watching a video game. But will video games follow Avatar in the push for 3D?

In one sense, video games beat movies to the 3D scene by a fair distance. After all, the software of games has technically supported 3D rendering as long as video cards have been used in the display of 3D graphics. All it takes to do 3D is to render a single slightly offset 2D image for each eye, and… well, the rest is hardware implementation details!

But that’s the catch. Several solutions do exist, from the most easily understood but worst quality anaglyph image splitting using red/blue glasses to the virtual reality goggles that briefly stormed the scene in the 90s then quickly flared out when their cost and drawbacks (low resolution, nausea) proved too much to be marketable. Most promising in my view from both experience and a theoretical standpoint is using polarized glasses, which is how the 3D in Avatar works, but this requires more specialized (and expensive) technology on the side of the display than the older and cheaper red/blue image splitting. Gamers can get fancy monitors that support rendering 3D games using polarized light already, but the cleanness of the image varies from game to game, and the effect isn’t perfect.

I personally suspect that Avatar will push games in this direction just as I expect it will for movies. But the transition won’t be as difficult for developers; after all, they’ve been making games in 3D for over a decade now. The real people who need to be pushed in order for this to happen aren’t game developers, but gamers themselves, whose increased interest and demand for stereoscopic 3D technology in mainstream entertainment will do more to drive 3D hardware development and sales than anything else.


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This is not about propaganda, preaching, or condemning
Real world religion in video games is almost off-limits, by some unspoken convention. If you share that skepticism, don’t panic. This isn’t the kind of talk you might fear it is.

Merry Christmas and Happy Holidays! In celebration of Christmas, I’d like to refer you to a talk one of my classmates gave on The Bible in Games.

I first worked with Kye when we were both freshmen, and were blindly grouped together with three other students for our mutual love of The Legend of Zelda: Ocarina of Time. After we jointly wrote a paper arguing for why that was the best game ever made, we worked together to develop Snowglobe: The Secret of Freon, a text-based strategy game with spiritual roots in The Oregon Trail. Kye was our technical director because he was the one with the most programming experience, having previously studied Java in high school. Thanks entirely to our strong dynamics and skilled team, Snowglobe was a great success (at least as student text based game projects go), and Kye and I would later be two of only five students to be permitted to transfer into the new Game Design program after our sophomore years.

Now Kye is approaching his last semester at DigiPen and is starting to look for a job. He currently has a website and blog up, Emphatic Experiences. This is a great opportunity, since his most recent post has a video and audio presentation on The Bible in Games, and comes highly recommended. It not only applies to the Bible in games, but to the application of real world theology in general. This is a talk he’s given twice now in school, and it addresses the risks, benefits, and stigma associated with carrying religious themes into video games, and talks about different ways of doing it. The talk is interesting, good, and timely. So if you haven’t already, go ahead and click over and check it out — it will only take 15 minutes of your time.

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Starcaft 2 Third Person Shooter Mod
Giving level designers potent tools allows them to surprise you. Blizzard promises that Starcraft 2’s campaign editor will do just that, empowering players to create entirely new game types, like this third person shooter mod created in-house.

Making your level designers happy and creating emergent gameplay are actually not very different things. They aren’t linked in the sense that they go hand in hand, but they do need the same things to craft interesting experiences. Emergent gameplay can be encouraged by increasing the number of verbs available to the player, objects in the world, and interactions between verbs, objects, and object behaviors. Empowering level designers works much the same way — the more parts they can play with in the editor, the more things they can do with those parts, and the more mechanics in the game, the more often they will surprise you and the more interesting and varied the gameplay they can create.

A great example of this is Little Big Planet. We might say this game has emergent gameplay because players can make incredible adventures up to and including tetris, space invaders, and asteroid lander games, which are then published online for other players to use, far above and beyond the content put into the game. But it’s not really emergent gameplay, per se — it’s that they packaged a level editor into the game, and the level editor exposes immense potential for interaction and creativity. They cast their audience as level designers and then greatly empowered them.

It doesn’t take a mountain of complexity to gain traction here, just interacting mechanics and interesting tools. Given only blocks, running, and jumping, a good level designer can still maintain the player’s interest in a platformer for a fair amount of time. But give them spikes, fall damage, breakable floors, pressure plates, openable gates, weapons, enemies, and health potions, and they’ll build you Prince of Persia.

More than just opening up possibilities, the more level designers are empowered through the interaction of the content and mechanics, the more they will have fun making levels. Creating a game becomes its own game to them; they play and entertain at the same time. It’s like dungeon mastering. It’s why they love game design.

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Anti-TD Screenshot
A tower defense game where you’re controlling the attackers, instead of the towers? You can even pick which entrance to launch your troops from and direct them in mid-level. Too bad the shortest distance from each possible entrance to the exit crosses the exact same number and types of towers, making this a nearly meaningless choice…

This is a bit of a long post, since I’ll be looking at a game that I like the concept of, but that I think didn’t meet its potential. Once breaking the game down and identifying what I see as the problems with it, I’ll start to explore strategies that I would look at to improve the design.

Tower defense games are a genre of (usually flash) strategy games, with origins in RTS map mods, in which the player places a series of usually upgradable fixed turret defenses in the path of oncoming waves of increasingly powerful enemies. The goal is to defeat all of the enemies in each wave, and place and upgrade more powerful towers to overcome more powerful waves.

The concept is simple but it has a lot of traction, and in its simplicity, and the ease with which clones can be created, it has exposed many variants that make it interesting to me from a design standpoint. The genre comes in two basic forms, one track-based, and one in which you can build your own maze. The successful Bloons Tower Defense and Desktop Tower Defense series are examples from each that demonstrate a high level of polish and careful design. The track-based ones are super easy to make as games go, and are a dime a dozen on the internet. There’s even a series where someone made a “make your own tower defense game” game, where you lay down the track and set values for the towers and so on.

In this post I’m going to look at one of the most unusual games in this genre, Anti-TD. Anti-TD throws the genre on its head: There is a track based tower defense game, but you’re not the player placing the towers around the track. You’re the computer sending the troops out. To win each level, you need to exhaust the player’s lives. I like this concept (I actually thought about doing something similar in the past), but in practice, it’s pretty dry mechanically. Go ahead and try it out yourself.

On face value, this isn’t surprising. Sending a bunch of units you don’t really control to get slaughtered in a gauntlet isn’t very stimulating. But I believe the problem runs a bit deeper than that — the underlying tower defense game just isn’t well designed, and it doesn’t present strategic options to the player. Fortunately, this is solvable.

Your units are all modeled using a speed and a resistance value. I assume resistance is hit points. Typically, in a tower defense game, the relationship between these variables matters. The high speed, low hit points enemies dart past your slower firing towers, shrug off splash damage (as they’re usually a bit spaced out) and reduce the DPS of any towers that do more damage in one shot than they have health, while the low speed, high hit points enemies don’t break a sweat at towers designed to slow you down, and test your ability to focus large amounts of raw damage onto the field.

In Anti-TD, you have units like these, but they don’t matter. The AI builds towers seemingly at random, distributing equally among its tower types and showing no particular strengths or weaknesses. As a result, all strategies tend toward the same result. The towers themselves are missing some key points too. First, they almost all have a high firing rate, so the unique advantage of fast units is essentially eliminated. Second, there are no splash damage attacks, so there is no reason to spread your units out. Third, they have no slow attacks, so the unique advantage of heavy units is essentially eliminated. Instead, the unit selection comes down to this: Which unit has the highest speed multiplied by resistance, and how tightly can I pack them?

Of course there’s cost too, you have to spend money for these units. Gaining money comes from the units traversing the track: Each tile of progress for each unit gives you a fixed income based on the map. This, however, means that speed multiplied by resistance is not just a measure of how many towers the unit can pass before dying, it’s also a measure of how much income that unit will give you before dying. Dividing this factor — I call it survivability — by the price of the unit gives you a measure of how lucrative it is to deploy that unit.

I’ve performed this analysis on every unit in the game. The result is two dominant units.

The first is the TRT-L unit, which is extremely slow but has disproportionately strong armor. This unit is the most cost efficient unit in the game, making it the most lucrative to deploy. Spamming TRT-L units (specifically the lowest level of them, which are the absolute most efficient) to start a difficult will earn you more money than any other unit combination in the game.

The second dominant unit is the Razzo, specifically the highest level Razzo. Not only is it very efficient itself, but it has the highest raw survivability of any unit. It’s not as tough as the TRT-L, but it’s a lot faster, and that means the towers can’t inflict their DPS for very long. Razzos are expensive, and all units are more effective if massed so that towers can’t apply their full DPS to each incoming unit, so it’s best to start with TRT-Ls until you have enough money to send a swarm of Razzos. Typically the Razzos will raise money themselves once they get going, though, especially as they’re likely to complete the map and get a substantial completion bonus for their trouble.

This is a mid- to late-game strategy, since you can’t afford to deploy these units early on, and the income for each step of progress in early levels is too low to justify sending expensive units out, since it’s impossible to recoup the cost, even if they get all the way through. In the super late game, this strategy is then complemented by aerial units. You usually don’t have to think much about aerial units; any tower can hit them just the same, so they’re subject to the same calculation, and they’re inferior. Later on however, they can slip past your slower ground units by bypassing the distracted heavy surface towers. This increases their efficiency, but they also are subject to additional firepower. In other words, the most efficient flier complementing the most efficient ground units will maximize your ability to reach the goal on extremely difficult maps.

I think the game really just needs an injection of interesting choices and sense of achievement. First thing I would do would be to strip out some of the more meaningless choices: Instead of having a large table of units that are, for the most part, just points on a one dimensional usefulness spectrum, I would suggest a handful of behavioral archetypes. Your classic medium strength and speed unit, a sprinter, a heavy, a class or two of fliers, some spawner/carrier units, maybe some that have special defenses like shields that deflect certain attacks better than others or buff others. Start the player out with only a couple, but as the player progresses in the game, let them allocate upgrade points toward unlocking new types. Instead of offering differently priced strengths of these units, offer just one, but let the player algorithmically scale their global power level between waves.

Then, I would focus on giving the game more of a strategic element. Path choice in Anti-TD comes down to picking the path that crosses over cool buffs, a feature I very uncharitably suspect was added after the initial prototypes of the concept didn’t deliver on being fun enough. Instead, I would let the AI build unbalanced tower layouts. If the player favors a certain path, you could let the AI drop more towers on that path, but another option is to simply have the AI’s towers upgrade when they reach a certain amount of experience. I’d also differentiate the towers significantly, and allow certain tower choices to be better counters for certain unit choices. Have a tower that excels at fighting fast units, a tower that punches through heavily armored units, and so on. Combined with experience-based upgrades and a reactive building algorithm, this would provide a negative feedback mechanic on the most effective strategies. It might even be worth encouraging the AI to be biased in favor of unbalanced tower type distributions too — after all, one of the weaknesses of Anti-TD is that the player can’t exploit weaknesses in the tower pattern because there aren’t any.

Finally, there are a few miscellaneous things that I think would really give some extra punch to the game and the sense of playing as the enemy in a tower defense game. First, I’d give the AI player a cursor and GUI, and let you watch the computer actively placing (and perhaps upgrading) towers in the path of the player’s units, responding to each wave by either sitting still and letting it come, or desperately trying to toughen the defenses. Second, I would force the player to prepare and release enemies in waves, with feedback on the outcome for the player and the AI after each wave. Every ten waves or so, the player could prepare a special boss wave. During waves, the player’s unit deployment GUI could be hidden entirely, instead using the AI’s tower building GUI. Between waves, the game could pause and the tower building pane overwritten with a darker, more evil unit deployment GUI, for preparing the next wave. Third, I would display direct feedback on things the tower-building computer player is thinking, from the more direct exposure of AI reasoning in “X is worried about fast units” to a more flavorful exposure of confidence in “X is stepping away to get a soda”.

As much as I knock Anti-TD, I think it’s an interesting concept and a fun one to explore. As games like Dungeon Keeper have long before shown, the fantasy of swapping roles and playing as the enemy is one that resonates with people. The difficulty is that these games have the potential to only be fun in one direction. I think half the real challenge is just to find the fun in level design, and expose that to the player. Of course, the designer is really on the player’s side when making levels, so a bit of creativity is needed in the adaptation, but in most cases I believe it can be done. For Anti-TD, it’s a first attempt. I see it like a prototype; it’s fun to look at how the concept can be expanded and changed to hopefully design a more fun game.

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As time passes, many beautiful things are created by the many creative and talented people in the world today. In the games industry, new amazing games like Dragon Age: Origins and Left 4 Dead are released. In movies, James Cameron’s Avatar and The Fantastic Mr. Fox. Webcomics reveal their work over time, and some of the best update infrequently or take months for storylines to unfold. It’s like getting a prize just for being alive. I love it.

In fact, one of these creations is indirectly responsible for my choice of career. In 2002, three brothers in Maryland made this Star Wars fan film, Art of the Saber:

This video struck me. It was beautiful on many counts, all interacting — the choice of music (later changed to avoid copyright infringement, but this is the original), the narration of the civil war letter, the quality of the special effects, and the choreography of the fighting, all combined to make a very pleasurable experience in only a couple minutes. I watched it repeatedly. It affected me. I wanted to touch people in the same way that this video touched me. I devoted my life to creating beauty, and eventually, chose to focus that pursuit on making games.

It gives me such pleasure that beautiful things like this are all still being generated, across the world, and that I’m only one small part of this. So let me tell you about my very latest discovery.

I used to watch a lot of Star Wars fan films. One of the older and more beloved fan films on the internet was Troops, based on a mash-up of COPS and Star Wars stormtroopers:

The people who made Troops eventually started the vastly more ambitious project IMPS: The Relentless, again based on the idea of following Imperial troops. Originally envisioned as a series of eight chapters over twenty minutes each, the first chapter was released something like five years ago, and the second never materialized:

But I never gave up. Today, I went back and checked the site again, and what do you know. After five years, the second chapter is up.

There’s a certain magic to things like this. I appreciate everyone who creates art and beauty. We live in such a wonderful time, when access to so many amazing things is right at our fingertips. It’s hard to imagine not being happy.

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