In this diary, I’ll be discussing aspects of the animation process for our tower defense title, Defense Grid: The Awakening.

The visual tone of the game was set by the various artists involved.  This was done in a very collaborative environment – typical of game development at Hidden Path.  We discussed and decided how the towers and creatures should move, and what sort of impact the animations should have. 

Towers:

In the game, the player character erects defensive towers from predefined slots in each level. Since we wanted to preserve the fundamental strategy of tower positioning, we didn’t want to have towers move around like characters, but we did want them to raise, lower, attack, and scan for the next target. We also planned special idle motions, and reload sequences, but most of the towers’ animation ‘zing’ is in the way they raise and lower, mechanically blossoming into death- dealing machines of doom. As we were starting to spec out some of our planned idles, T.J., one of the programmers, devised a procedural way for the turrets to “scan” for the next target. I was happy enough with the result to scratch most of the idle animations off the list. It was much less repetitive and more convincing than a looping idle animation created by an artist. Players will still see a standard idle here and there, such as a rotating radar dish, but most were replaced by T.J.’s great solution.

Accommodating the procedural motion wasn’t without its challenges – it meant re-rigging some of the towers to have yaw and pitch bones that the programmers could control (even in instances where a tower did not yaw or pitch!) but it was ultimately worth it, and I still love the way the towers all look around separately, searching for their next unlucky victim. 

Aliens:

The aliens consist of the invading hordes intent on robbing the player of his precious power cores. They appear in increasingly difficult waves made up of different types of creatures with different stats. They move intently, focused on their goal, undeterred by the slaughter into which they march.

As models were completed, I began rigging the most complex one first -- the Juggernaut. We used 3d Studio Max‘s biped rig, posed as a quadruped. After rigging and skinning were completed, I created the first walk and death cycles to set the look and feel for our animation team.  For additional direction, I tweaked the animation timing to work appropriately with the pacing of game play.  The animation crew took it from there.

Though we started with a more complex list that included lots of animations, gameplay evolved such that we narrowed the list down to basically walking and dying. Those two animations had to convey each alien’s personality.  Differentiating was a difficult task.  Each alien has a couple of death animations, for variety, but the walks were pretty standard and so presented a tougher problem.  To solve it, we added “leans” that we blended into their animations as the aliens turned corners.  That added a lot to an otherwise unremarkable animation.  I was very pleased with the way the alien animations turned out.  Of course, I’m never completely satisfied.  If we had additional time and budget, I would have liked to see the deaths have a bit more inertia, but they definitely convey what they need to with a lot of character from game view.

Overall, I’m really happy with the animation in Defense Grid. I think it is a substantially better experience than what other tower defense games have to offer. I still get giddy watching the towers unfold, and it’s always satisfying to watch a particularly tough alien finally crumple to the ground. I hope you enjoy playing Defense Grid: The Awakening, and thanks for reading!

As a software engineer at HPE, I get to develop tools that enable the team to work more productively.  Improved productivity results in more game content and a more gratifying experience for the player.  On Defense Grid: The Awakening, I worked on new tools that helped our artists and designers develop more content so the player gets even more from the game.

Asset Viewer

One of the concerns when developing a game is how long it takes for an artist to be able to see their art as it would look in the game.  Artists use many different software tools to make characters and environments come to life, but those tools usually don't know anything about how the art will be drawn in the game.  As a result, we generally create some additional software to allow the artists to very quickly be able to see and evaluate their content in the game engine.

A new Asset Viewer software system has been a particularly fun element of programming for Defense Grid.  This tool allowed our artists to take new art (including towers, environments and particle effects) and view that art as it would be seen in the game.  This allows the artists to immediately get an idea of how object animations or lighting will look without having to wait for a new build.  Making all the rendered content for a game is a huge task, so helping the artists out with the Asset Viewer was useful for them and a fun program for me to create.

Rule Sets

Another one of the cool things I worked on was the implementation of Rule Sets in the game engine.  Rule Sets allow the designer to set up specific ways in which a game level can be played.  The more ways you can set up a level, the more hours of game play our designers can dream up.  We might give you lots of resources with which to build up your defenses, but then also make the enemy units stronger.  Or perhaps, when playing on a higher difficulty setting, you have to fend off the invaders with only a limited set of tower types.

As an example, when you first play the "Fire Control" level you are playing with a set of rules that makes it challenging to earn a gold medal.  But once you've unlocked the additional play modes you get to challenge yourself by trying to play the same level with tougher aliens, limited number of towers, or only green (first-level) towers.  Each of these additional modes has rules that are uniquely set up by the designer in order to provide the player more fun, additional game play and new challenges.

During play-testing it was really cool to see how we could play a level with one rule set and then play it again with a different rule set; resulting in two completely different and exciting encounters, despite it being the same map!  Our designers continued to tweak the rule sets for each game level to ensure that no matter what the play style, you'll have a really enjoyable experience.

Enabling the artists and designers on the team to create content better and faster has been very rewarding.  I hope it leads to you having a lot of fun with Defense Grid.

Greetings!  My name is John Daud and I'm a designer at Hidden Path Entertainment.  Our latest project is a tower defense game called Defense Grid: The Awakening.  Our goal for this title was to take all of the fun we were having playing web browser tower defense games and add some production value to the genre through complex sound design, gorgeous art and a compelling story.

Defense Grid was principally inspired by the imagination of our CTO and one of the company founders, Michael Austin.  Michael had played a number of tower defense games and was fascinated by the game mechanic, but believed that there was great opportunity for improvement in graphical fidelity and game play.  He discussed his idea with Mark Terrano, another founder and our Design Director.  Mark bought into Michael's vision and assembled a proposal.  From there, the principals generated a great design document that set the product tone.

But the design contribution went far beyond Michael and Mark.  Design at Hidden Path is a truly collaborative effort that involves everyone on staff.  Every member of the team has a wealth of game development experience and a broad knowledge of many game styles.  Consequently, the team considers all ideas and suggestions, regardless of whether the source is an artist, a programmer or a designer.  With such a strong group working on the title it was no surprise that in a matter of months we were already playing a fun, addicting and great looking prototype level.  After we agreed on what made the game fun, we just needed more content.  So my primary role on the project was to design and build many new levels, leveraging off of that initial prototype.

To construct level maps, we used a proprietary map editor built specifically for this title. The tool allowed me as a level designer to either construct constrained paths, open platforms or combinations of both.  In tower defense games, the antagonist comes into the map messes up your world (in our our case they steal precious Power Cores) and leaves, either from the point of entry or a separate exit.  So we knew we needed spawn points, exit points, and power core positions defined in the editor.  One of the most exciting features of our map editor tool is the procedurally generated geometry.  The constrained paths - where the landscape of the environment determines where the enemies can move - are defined by series of connected waypoints.  These automatically generate the path geometry complete with the path surface, guard rail, lights, support structure, pipes, etc.  This technology also allows sections of the map that are designated buildable areas to be procedurally generated with the sci-fi industrial design appearance we wanted.  With the game play-specific elements procedurally created, the artists can focus on geometry in the levels that really brings the environment to life and truly takes the Defense Grid aesthetic to a high level.  One of the coolest parts of the process was seeing what the artists created out of my collection of paths and tower platforms. 

Of course, making each level fun and unique was a critical part of my job. I had many different variables to play with to accomplish this. One of the cool things about tower defense game design is the ability to "tweak the knobs" in order to adjust the game play experience: the number of enemies attacking, the time between waves, the type and strength of the invaders versus the types of towers at the player's disposal, how many resources the player has at the start in order to build those towers, the number of spaces available to build in... all of these variables can be adjusted to subtly or radically change the player experience.  And while surviving a Defense Grid level is certainly fun, another effect of these many variables is the desire to replay the level in order to achieve a better score or a higher medal value.  "Did I need to build that last tower?" "What if I frontload my defenses instead of building near my cores?"  "Maybe the Inferno tower would be more effective than the Laser in that one build spot..."  "How did that guy finish the mission with 800 more resources than me?"  As a level designer, I want to know the ideal strategy for any particular mission, and I want to provide the player with a challenge while they search for the perfect defense. Personally, it is great to hear about someone waking up after playing our game the night before with an inspiration for a better defensive strategy for some particular mission in our game.     

I am thrilled that even after all of the months of hard work put into this game that the development team still can't stop playing the thing.  I can honestly say that I had a great time working on this game, and I am very proud of Defense Grid.  I hope you share my excitement, and that this diary adds to your appreciation of the game.  See you on the leader boards!

Hi, I'm T.J. Martin, a game programmer at Hidden Path on the team that created Defense Grid: The Awakening.  We've just finished the final polish stages of the product, and it feels great.  I think we've got a challenging, addictive game that's fun to play and beautiful to look at.

When I think back to what the key things were that allowed us to get to this stage, I focus on two things:  1 - allowing the designers to have the ability to efficiently experiment with design concepts, and 2 - the excellent communication and problem solving techniques the team used.

The tower defense format provides a simple, but rigid, system of rules. Since this system established the basic game play, we used this rule set as a canvas to explore more subtle design ideas and play with game balance.  We wanted our designers to be able to work as freely as possible, so we thought about content creation from the very beginning of Defense Grid.  One of my main tasks was to allow the designers to create levels that were completely playable without any programmer or artist intervention. The result was a level editor that actually generated geometry for testing purposes.  Only after the level design was nailed down would the artists would go through and make it look beautiful. Since Tower Defense is a genre that is largely about optimization and efficiency, it was important to be able to tweak every little detail to make every level, monster and tower as fun as possible. We made an effort to ensure that any number or setting could be modified by a designer without having to wait for someone to change code.

One of the things I like most about Hidden Path is the rapid flow of information. We work in open environments where everyone is free to bounce ideas around. No one hides in an office and creates features in isolation. Any feature has probably been thought about and discussed by multiple people from art, programming and design. This low communication barrier also allows programmers to better empower designers. We don't simply read a document and then make it happen. We work with the designers. If we have a question or suggestion, we can bring it to them directly instead of waiting for an open slot on their Outlook calendar. This lets us make sure that our game stays fun and that we all love the final product.

One of the most interesting design areas has been assigning roles to individual towers. I have always felt that, in any game, different pieces of your arsenal should be fundamentally and functionally different. Just changing numbers and adding a new visual effect is not enough! Anytime we felt that two towers were becoming too similar, we addressed it. At one point, we had a tower that wasn't really working out. Instead of just cutting it or letting it go unaddressed, we got around a whiteboard and discussed what made the tower unique and how we could keep that element. At the end, we had completely redesigned two towers. No meetings were scheduled. No formal change requests were written. We exchanged ideas collaboratively until we arrived at the right answer, and we made it happen.

This kind of cooperation and these thought processes are what enable us to create games we are proud of.  I knew we were on the road to achieving this goal with Defense Grid when we all started competing with each other for better scores and breaking down strategy on a whiteboard to be better at our own game.   The team dynamics have really helped build a great game experience.