It's hard to imagine life in a postapocalyptic world without conflict. And the way we humans like to solve it is straight violence. So let's see what our combat system looks like.
First, we decide that we don't want combat to be somewhat tactical. You should make good decisions to achieve the best result. And since we make a mobile game, we didn't want an environment to be a factor. You should not lose to the boss, because someone pushed you in the metro. So it should be something turn-based. But what kind? Should it be team turn? Or each character has its own turn? Should they be fixed? I can and probably would make a full article or two, and how you can make turn-based combat. In the end, we decide to go for the Conditional Turn-Based Battle system. You can see it in Final Fantasy X. On the surface it's pretty simple. Character spend AP to perform a move. Then we move him somewhere in turn-queue. The bigger impact the skill has on combat situation - more AP it cost. Bigger cost will move the character further back in the queue. If you invest in character speed, he will be able to act more frequently than one with high strength. I will tell more about stats and how they engage with each other some next time.
After deciding that combat system will be turn-based we started to look at the optimal player party size. After some tests, we settle on the 4-man party. It looked big enough, to give players the ability to test different strategies. And still left the place on the screen for some action. We won't force you to take the full party with you each time. You can go with as many mercenaries as you want. Party composition is important. You should explore all possible combinations, to find which suit best for your goals. That's the other part of "Exploration as core pillar"
In the next diary we will tell about characters. Here you can see small video with combat encounter from our pre-alpha version of the game.