Dev Blog

Dev Blog 26: Reinventing the (command) wheel

We’ve spent the past 4 months or so play testing with a traditional MOBA lane and minion wave structure. Recently, I’ve come to the conclusion that this doesn’t fit Revn’s gameplay perfectly, and in this blog I’ll be explaining how I came to this conclusion.

In a traditional MOBA, minions are spawned automatically, in waves, and follow a set path down a “lane”, a linear section of the map with clearly defined objectives, routes, and obstacles such as enemy towers.

Players in Revn are able to build fortifications. This is an important part of Revn’s design and one of the things that set it apart from other third person shooters and MOBAs. Of course, buildings are a very complex and dynamic factor in the gameplay because players are free to build anything they can imagine.

Meanwhile, minion waves that follow lanes are considerably more single-minded and simple in their design. They have one objective, and one path to get there. The behavior tree for a minion AI in a lane is pretty simple, and looks something like this:

What we’ve found is, when something so simple and single-minded is placed in competition against an incredibly dynamic and complex system, problems begin to emerge. Minions are unable to adapt their strategy and goals to intelligently navigate the complex structures that players build.

With this in mind we’ve decided to reinvent the proverbial wheel.

Many months ago, back in late 2018, Revn had its first AI system. It was a squad base system that allowed players to spawn a small number of troops and issue basic commands using a command wheel.

The AI was a bit sporadic and was often frustrating to work with because of their randomize movement patterns, but they would generally follow commands that a player gave them. They needed work, but we didn’t have the developer staff to give them the attention they deserved, so we pulled the system for a few months.

Then, earlier this year, we switch to a minion wave system that automatically spawned minions. They were more effective and easier to program. We made the switch to a more traditional three lane map structure. We did all this to simplify the AI and to create a structured objective system that would allow us to more efficiently play test the abilities and other parts of the game.

Now that we feel the abilities and resource gathering are working as intended, it’s time to revisit the AI and map structure. To combat the dynamic nature of player built defenses, we’re bringing back player-directed minion squads. The squad AI will focus on assisting their player. This is in contrast to a traditional MOBA minion, where it is often the player who “assists” the minions to destroy an objective.

Squad AI will either follow the player around the map, or can be given commands to move to specific locations. We are developing additional commands, and I’m excited to see what these AI evolve into. The command wheel has plenty of room for new mechanics and strategies!

– Silas