TD Challenge

Tower Defense Twisted

TD Challenge is a challenge I gave to myself to see if I could create a tower defense game in UDK using only Kismet. The demo has three kinds of units and allows for up to six units to be created. If an enemy makes it to their end destination, the player takes damage. Let too many through and it’s game over!

Production Notes

  • Engine: Unreal Development Kit
  • Built entirely through kismet and the Unreal editor
  • Solo Project
  • Primary focuses
    • Advanced Kismet scripting
    • Interesting player experience

Video Overview

The video above shows the test map the prototype was built in. The arena has multiple heights of pathways that can be used by enemies, towers, and the player. The position of the units in the video can be seen below. The video shows off some basic strategy about using different kinds of units. Notice how Shock Rifle units are used to shoot down long distances while Rocket Launcher and Link Gun units are used at much closer quarters. Other elements such as splash damage, alternate firing modes and self damage come into effect when placing units.

Below there are three images depicting the position of the units when they are summoned and where they are placed to fight the enemy.

Design Evolution

Bringing in the FPS
Originally the player was to have no active role in damaging enemies and would instead rely entirely on the towers to destroy enemies. However, this left the player with little to do while the actual action of the game occurred. Given that UDK is built from Unreal Tournament 3, it made sense to use the built in shooting and movement mechanics to give the player a fast paced contrast to the slower paced strategy of setting up towers. It also allowed for a greater degree of strategic flexibility, as players could risk using less towers and attempt to compensate with their own effectiveness.

Too many towers
Originally I had planned on using vehicles as towers as well as regular tower units. At first this proved difficult for technical reasons, but later I realized that the inclusions of vehicles was more stress on the player than it was worth since vehicles were difficult to maneuver and added nothing special to the gameplay. Often times, vehicles would be far too effective in the hands of a player as well. All of this meant that vehicles were simply subtracting from the overall play experience, so I removed them to focus on the core engagement.

Possible Additions

There are many additions I would love to add to this at a later date. Chief among them is the addition of an in game economy. This system would be the basis for many of the other additions I would make, including more weapons, unit kinds, traps and new parts of the map. The economy would follow the basic structure of the average tower defense economy where each kind of tower costs a specific amount of currency and defeating enemies gives players currency.

Additional Content
With an economy in place, content to purchase is needed. These additions would include new weapons and traps for the player, new kinds of tower units, and new parts of the map that can be purchased for increased strategic positioning. Together these would allow for incredible strategic depth. Some players would choose to spend most of their money on units, edging the gameplay more toward tower defense and strategy, while other players may choose to buy themselves powerful weapons, bringing the gameplay more to the first person shooter space. For example, one player may decide to purchase a sniper rifle and a sniping tower because they enjoy this kind of gameplay, and then also use close range Link Gun Units to balance with the player’s sniper rifle.

Shooter Rewards
In order to integrate the economy fittingly into the existing game, the economy would have to take advantage of various bonuses, such as a bonus for getting a double kill, or additional points for each kill in a killing spree. This would be important for combining the shooter and tower defense elements cohesively.

Post Mortem

This prototype was a great success on many fronts. I became very familiar with the intricacies of UDK and Kismet, while creating a unique and interesting style of gameplay with plenty of room for expansion. This project laid the basis for several of my later projects, allowing me to use UDK to a much greater extent. From a design perspective I also learned how important it is to test a concept repeatedly and be aware of how the addition of a single mechanic or element can dramatically change a game. Originally, the player could not shoot while enemies had spawned, but realized that it was quite boring, and giving the player something to do both filled the space, and helped them feel more engaged with the action that was going on.