Well I've seen ideas about multiplayer so if you ever decide to accept their idea to add multiplayer then MAYBE you can add this gamemode

Humans vs Robots.It obviously fits. It takes place with a bunch of humans (It should be at least 10-15 human players)
Fighting and working together to try and not have their home destroyed by the everlasting robot forces.

Its basically infection from call of duty
Or maybe you can have it different and make it be sometime of war thingy