In any event, whatever style of gameplay they choose, basic guidelines:
- Controls, controls, controls:
Focus on precision and responsiveness, instead of "realism". I can count a few out of dozens of examples where it added to gameplay and none are fast paced action oriented. Try to run a race without tying your shoe laces...that's Exactly how it feels like. Stop repeating Rockstar's mistakes on this.
- Open and Interactive/Intuitive gameplay:
Going between stealth, melee, ranged combat should feel easy and efortless. No messages popping on the screen: You cannot do action x because we invented some artifical obstruction. Player should be able to interact with environment, just as outside of combat and use this to his advantage. No invisible barriers which prevent enemy pursuit( unless there are logical world restrictions).
Open world games have (typically) weaker gameplay mechanics than more "linear" games, but they are at their best in spontaneous, non scripted scenarios as result of physics/AI/Environment interaction which force the player to quickly adapt to situation ( I could write a small book on those I've had in Far Cry series and none of them were hand signed by developers).
Do this right, from AI programming to interaction with world objects, and the "density" of content in Night City will allow a ton of opportunities for interesting emergent gameplay.
- Less soft lock based systems/More manual control:
While these improve the "flow" of gameplay and typically make it more "stylish", in games of longer length, they become more of a detriment as they make it less engaging with game makes decisions for you. And any imprecision in their design, makes the experience more frustrating. Focus on giving the fullest control to the player, in and out of combat.
- Punishment/Reward system within mechanics, system that rewards mobility, high risk and experimentation, high skill ceiling, customizable difficulty settings ( more oriented on AI dynamic than turning enemies into bullet sponges)