Just Cause 4: Los Demonios

Prototyping the Demon Infestation

My primary focus on Los Demonios was designing the first playable prototype for our Demon Infestation.  Our main design directive was that we wanted our core gameplay experience to be something reminiscent of the Just Cause 3 liberation system.

Here are the rules we came up with for our Demon Infestations:
-Each Infestation has (at least) one Source
-Each Source is protected by a network of Demonic Tendrils
-Each Demonic Tendril is linked to a Fungal Growth
-Destroying a Fungal Growth will cause the linked Demonic Tendril to recede into the Source
-Causing all Demonic Tendrils to recede into the Source will make the Source vulnerable, and allow the player to destroy it
-An active source will create a Demon Dome around the afflicted area
-Vehicles that enter a Demon Dome will malfunction and crash

To sum it up, the player must find and destroy all the fungal growths in order to reveal the Source, and then they must destroy that too.

Prototype Vs Final Demon Infestation - Comparison Videos

The top video contains some of the highlights from my original prototype, and the bottom video is final gameplay.  The prototype was created about one month into development, and the final version came maybe six months later.

The top video shows some of our earliest explorations with overall area size, vehicle and AI behavior, and the basic destruction gameplay loop.  ​The prototype was made quickly and cheaply, reusing assets from the base game.  All the major elements of the Demon Infestation design are present in the prototype, which allowed the team to judge the potential of this design.

There were two major benefits to making the original prototype.  Firstly, it helped demonstrate what the Design team wanted to make, which is useful for aligning the rest of the team.  People are able to work most effectively when they understand what they are working towards.  Secondly, any major concerns or questions about the overall design can be addressed early in the development cycle, rather than right at the end.  This all results in a stronger final product.