Foxhole

The core tenet of this game is Player-Driven Narrative that emerges as a result of collaborating with other players on a massive scale.
A lot of the design decisions in this game is rooted in limits to how many players can be in the map at any one time.
SiegeCamp - Game Developers of Foxhole
Devblog

Cogmind

When integrating complexity, it is important to make interfacing with this complexity fun for the players.
Develop multiplayer systems for the game early .
Features an interesting use of modular units and simulated attacks (everything from missile trajectories to radar and radar jamming is simulated)
Be careful and feel the pulse of the playerbase before making difficult game design decisions. See the feedback from this video. Know your demographic and know why people play your game.
Eridanus Industries