Building Rational Units

Tuesday, September 1, 2015 Discuss on the forums

Welcome to another monthly update! We hope everyone’s August was as interesting and productive as ours on the Legion TD 2 team. Now that we’re into the second half of the year, we’re going to be doing a series of monthly updates that focus a bit more on some of the technical challenges with Legion TD 2.

Last month, we made great progress on multiple systems that will power Legion TD 2. AI-controlled battles are the core of Legion gameplay, so today we’d like to give an overview of how that unit behavior works.

As you cheer and jeer at your units’ performances during each round, there’s quite a lot going on under the hood. At each moment of the battle units need to make decisions about the actions they should take. These actions take the form of unit orders — commands given to units, such as “Attack that enemy crab,” or “Attack-move towards the king area,” or “Cast shockwave at the position of the enemy quill shooter.”

In Legion TD 2, orders are automatically issued to units based on autocast conditions, which vary among different units and abilities. An offensive AOE ability might be autocast when it can hit at least 2 enemies, while a supportive healing ability might be autocast when it detects a wounded ally in range.

Once an order is issued, a unit must carry it out. Check out the flowchart below to see a breakdown of that process.

Unit Behaviour

Next month, we’ll be continuing to develop existing frameworks, with particular attention to the pathfinding system, which will manage the “Try to move closer” part of the behavior flowchart. We’re taking great care to develop strong frameworks to support new content for years to come.

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