Persistent Campaign Gamemode

WARNING: This would be very difficult to implement, and would require a large amount of work.

This gamemode wouldn't take place on a single map, nor would it have various, separate rounds. Instead, it uses several game instances, either actual separate but connected servers or several instances of the server code running on one machine. These server instances would communicate with a master server (which is what you actually "connect to", there isn't a listing item on the server list for each game instance) which runs the server-spanning gamemode logic. The server instances would all run individual maps and thus run their own, separate "games".

Each server instance would have teams of players as Guards. There would also be a few teams as Intruders that span across servers. This means that there would be many more Guards than Intruders across the server, but on each individual instance the number of Intruders would be close or equal to the number of Guards. Guards would not be informed of the presence of Intruders, and since Intruders can attack at any time, they have to remain vigilant.

Guards would pick out of "assignments", essentially objectives that would have to be protected for a long period of time. Picking an assignment would spawn you on the server playing the map you chose. You would earn money for successfully defending the objective associated with that map until the assignment is fulfilled (would take a long, potentially variable time, say 30 to 60 minutes).

Intruders would, as a team, pick a location to attempt to steal the objective(s) there. They do not get all the information about a location for free, i.e., they would know the map, objective type(s), and potential money earned, but not the exact objective(s), time left, or Guards at that location. They would earn money by successfully completing whatever objectives were at that map.

Money would be used to buy equipment such as ammo, Remote Charges, Binoculars, and so on (these would not be given for free, obviously). Money would be earned with the methods above, as well as by some of the same actions that give you XP (e.g. arresting someone). Money could also be used to buy intel for both teams, such as how many Guards are at a location or where a certain team of Intruders are.

Dying would both block you from respawning for 10 minutes as well as force you to join a different team. Arrested players would wiggle out of their cuffs after 5 minutes, unless either the enemy wins, or a member of the enemy team spends ~30 seconds to "kidnap" them, which earns their team much more money as well as counting you as dead for respawning purposes.

There is much more potential to this gamemode than this, and obviously you would be free to change the idea however you wish.