One reason I feel like the activity on PB2 has declined over time is the fact that PB2 has no player engaging gameplay besides 'play the maps and kill eachother.'
I looked through the first couple pages of suggestions and I did see this, but not exactly how I imagine it, so I'm doing a write-up on an idea I have in my head about it.
People have suggested alternate gamemodes, this is relevant to that, but more about how these gamemodes effect your profile and how they can make a more engaging community.
I feel like the clans system should be completed, but not only that, 'team' game modes, where clans can compete for a ranking on-site.
But I also feel if this feature is included, specific gamemodes should not effect Kill Death Ratios, but rather have a Wins / Losses ratio. This is to keep players playing the objectives rather than just going around killing everyone possible.
Not only would these additional gamemodes encourage community bonding, it would give players a new spin on gameplay and be able to have engaged combat with teammates that isn't purely about slaughtering other players, but rather reaching an objective of sorts. It would also make farming a lot less worth people's time because there are rankings besides 'people who killed the most other people'
Gamemodes I can suggest (Most already suggested but w/ever)
Capture The Flag (5-10 captures, requires like 5 people per team to begin)
King of the Hill (4-5 teams of 3 try to hold an area in a map, this area can be changed to other designated areas throughout the map before the game ends, team who holds the most players in these areas at match end wins)
CT vs T Basic (CS:GO format, where a team has a bomb carrier, and there are two plant sites where they can plant at. The other team defends these sites, and has like 40 seconds to defuse the bomb after planted before they lose. )
Escort (One team has to 'escort' a moving vehicle to the end of the map, and the vehicle will only move when their team is near it. the other team spawns at the opposite end and tries to stop them from escorting the payload within a given timeframe. No real defined parameters necessary)
Domination (Similar to CTF and King of the Hill, three designated zones can be captured by being occupied by one team. Captured zones add points over time, and teams compete to capture the majority of points in a match.)
CrateWars (Wasn't sure what to call this, but essentially, each team has a base with a crate or some sort of breakable object, and teams can acquire upgrades to guns or better weapons/health by going into a central area that connects all the bases together and capturing generated upgrades/guns/whatever. Players continue to respawn at their base until another player infiltrates it and destroys their crate. Obviously there would be a respawn limit and such, and the upgrades would have to be powerful enough to overpower any campers. There would also have to be a tiebreaker after a certain time all crates are destroyed, and at some point after that if not all players except a remaining winning team are alive, then they are teleported to the middle and some sort of lethal lightning or such keeps striking randomly until all the players die. I feel like this game mode would do particularly well with new swords included that can be upgraded along with better armor etc..)
Most of these gamemodes can be completed with complex trigger setups, but even then, they don't work player statistics and currently the only measured achievement players can gain is kills or deaths. Adding more game types and measuring success and failure in them, especially if a clan section is added where clans can compete against one another, would engage players and make them more concerned with being a part of a team.