"Survivalist: Invisible Strain". A third person zombie survial game. Has a story mode and a sandbox mode. Lots of mods already out for it as modders were working on it in beta stages. Has some pretty good complexity to social dynamics with you and others that give interesting emergent gameplay. Stuff like people developing love, grudges, gossiping and spiralling to raids and war or reputations developing for certain things.

You can be a lone wolf, small pack or try to blob up with others under you. Sort of vibes mix with Kenshi and Project Zomboid. Visually meh but superb gameplay. Kinda go in expecting to mess up and replay, it's part of the fun to see things explode and fall apart too. There's diferent grades of "infected" type zombies, each being more dangerous than the last but the final most dangerous kind is the invisible strain - an infected type that's smart and can infiltrate your group or others to cause mayhem like infighting, spreading infection and so on until it can rise up and destroy your group.

You can deliberately infect tools and weapons to get to others. Fire infected arrows at raiders. Gift infected stew to people you don't like. Watch as their own families have to murder them as they try to gnaw their faces off. Give them a low level infection and watch them worry and panic for days as they go around begging for a cure. Give them a high level one and watch them dramatically choke and turn in hardly any time and start mauling people in madness (like 28 days later).

Trading, social dynamics, base building, melee and ranged combat and stats you can train up.