I think mines should be limited to one or two per clip max, and they should expire after maybe 3 or 4 are placed. It's nothing but 100% pure cancer, in no way have the landmines improved GunZ gameplay in any way, regardless of gametype or how they are used. The landmines are exclusively a hindrance to player enjoyment, and amplify the worst and most frustrating aspects of the game.
Get rid of them all together, or HEAVILY limit them. People being able to mine off one hallway? Sure that's fine but joining a room that's been going for a long time and has nearly every spawn point HEAVILY landmined, especially on a high falling risk map like Stairway is so outside of the definition of fun and enjoyable, so outside of what GunZ players actually want.
Here's an example of why mines should be permanently removed or heavily limited
https://streamable.com/fuo90e
