Yeah, "Side Initiative" is an official variant rule for a D&D5e game. But they changed it to individual initiative plus concurrent turns for characters nearby. People playing MP are going to love that.
There´s a difference in Wasteland 3, and it´s that you usually have the option to rp or use one of your skills to determine who´s going first, your side of the enemy´s. You can trick them, intimidate them, or the dialogue option would determine if you to go first or if the enemies have the upper hand.
Not much of a fan of side initiative but the guys of Inxile made it in a very interesting way for an RPG like Wasteland 3.