The Making of Defense Grid

We've been posting developer diaries from the Defense Grid development team. You can read them here:

http://defensegrid.hiddenpath.com/view/content/meet_team

Some map screenshots

Waste Disposal and Last Stand are probably the hardest levels in the game. Anyone want to post their strategies? Here's some maps to help. I am not including a solution, but if you haven't seen these maps yet, it may be a bit of a spoiler.

Show Images (Spoiler Alert!)

Line of Sight

(I'm cheating a bit and copying partially from a post I made on the steam forums at http://forums.steampowered.com/forums/forumdisplay.php?f=487 )

Line of sight started out actually as more of a problem than a feature. We didn't really think about it until an early version of our game where the shooting-through-other-towers looked really awful. You don't really notice it until you try to do realistic graphics, and then your brain goes "That's wrong!"

We started out with 15 towers, I think, and the line of sight constraint really helped us tune them down. We tried to pick a subset of the towers such that each one was different and unique, and could be the best tower in a specific situation. I like, for instance, how line of sight affects the cannon-gun tradeoff. Guns need line of sight to be effective, since they are shooting constantly and any down time is bad. Since cannons are on a long cooldown, they can shoot the instant line of sight is available, and it actually doesn't hurt them that much. It leads to a natural "back row"-"front row" thing.

I grew to love it when I realized what a difference it makes for tower placement- when you have to consider your future plans for areas, there's a new depth of strategy. Suddenly in that clump of 4 towers right by two paths, they aren't all equal- there's a reason to pick, and the trade-offs are different for each tower. It was definitely a case where a problem turned into (what I think is) really fun gameplay!

Inferno

The inferno tower shoots a wide cone of napalm, roasting all the aliens within. It is balanced with the gun tower if it hits between 2-3 enemies on average while it is firing, and is much more powerful when there are more, and less useful when there are less.

The inferno tower is the first tower that does partial heat damage (which means it heats up enemies so they continue to take damage over time. This does have the side effect of reporting half of the damage it does under 'laser level 1' in your stats, but trust me, it's the inferno doing it!) This makes it more effective against fast enemies (who continue to take damage after they pass through), but less effective against shields (which make an alien immune to heat while they are up).

Here are the basic stats:

• Level 1 inferno tower - Total Cost: 150 - DPS: 8.5 - Range: 2.50 squares - Cone: 70 degrees
  
• Level 2 inferno tower - Total Cost: 450 - DPS: 23 - Range: 2.50 squares - Cone: 80 degrees
  
• Level 3 inferno tower - Total Cost: 1050 - DPS: 48 - Range: 2.50 squares - Cone: 90 degrees

The inferno targets the front enemy of the group, and any other enemies caught in its range will take equal damage. Because of their short range they are best when adjacent to the path (giving them the best cone area of affect).

Here are some good and bad inferno layouts:

Bad- infernos really should be next to the path - this one is not very efficient.

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Good- this one gets a good spread, but it's still angled relative to the path, so it doesn't get all the aliens it could.
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Best - this inferno will be aligned along the path a majority of the time. Note the position relative to the path of the aliens. Because it always targets the front, it will be stretched out along the path, making it maximally effective.

The Gun Tower

The gun tower was used as a baseline for all other towers in Defense Grid. Each upgrade of each tower was balanced around the level 1 gun, based on its overall utility across all situations.

Level 1 gun tower - Total Cost: 100 DPS: 10 Range: 3.50 squares
Level 2 gun tower - Total Cost: 300 DPS: 30 Range: 3.75 squares
Level 3 gun tower - Total Cost: 700 DPS: 70 Range: 4.00 squares

Originally, upgrades were 1:3:9 with the red towers being three times as powerful as amber towers, but it became too expensive to do the final upgrade (you had to wait around too long for the money), so we lowered it to 1:3:7. The first upgrade is twice the cost of the base tower, and the second is twice that cost.

It was interesting- originally I thought that upgrades needed to be more powerful since you had to save up the money to place them, but in actual playtesting this was offset by the fact that you could make extra use of a prime spot (one near a temporal tower, or one that was placed near a junction). In many tower defense games, upgrading is an easy decision- several waves in it becomes 'place-upgrade-upgrade, place-upgrade-upgrade', and it was important to us to try and find a balance where the upgrade decisions were actually meaningful and had tradeoffs.

The gun tower can shoot any alien within range, and is the best general purpose tower. Because it's so cheap and easy to put down, it's efficiency at level 1 is a little bit below average; however, by the 2nd upgrade the extra range brings it on par with the other towers. It is a front row gun- any tower in front of it limits the damage it can do, and so it should generally be placed as close to the path as possible.

Next: The inferno tower

Defense Grid

Hello!

This blog is about the game 'Defense Grid: The Awakening', recently released on Steam. I wanted a place to talk about the various mechanics of the towers and enemies, as well as to share some of how Defense Grid was created.