RadarJammer
So you don't want people to use radar on your server? First you'll probably add in the color codes to block radar with VoxelMap, and that's a good start, but there are other radar mods out there like CivRadar so you need something more. You might consider something like NoxRadarJammer, but a clever player will write their own radar mod to bypass that by determining which players are real. The solution? A radar jamming plugin that simply doesn't send player data for players you can't actually see! I've accomplished this using some lightweight calculations (in an asynchronous thread to prevent lag) to determine if players have a line of sight to each other. If the player A isn't within the field of view for player B, player B will never even know where player A is (unless he turns to look at him)
Mind posting the source to GitHub or similar?