Hello. Sorry for my English.
Now for the player there are no serious problems and opponents except other players. The game does not currently have the need to unite with other players except to kill other players.
If now developers remove all zombies from the card, then nothing will change much. And that's bad.
What needs to be changed:
1) zombies must be dangerous - when they hit your character, he must fall ill from infection and after 1-2 hours it’s possible to die, only special medicine that rarely appears in hospitals can cure you (when your character is healthy, we’ll have a chance to get infected by a zombie 30%, and when you are unwell, the chance of infection increases when hit.
Thus, you will try not to notice the zombies at all or to kill them at a distance so that they do not have time to hit you.
You can enter zombies with cold weapons such as a water pipe or equivalent, so that they have more damage.
2) It is necessary that the complexity of the game increase from the place of respawn as you move deeper into the map. So that people understand that it is more profitable to merge.
Now in cities and villages zombies can attack you and occasionally even kill. And in the forest is more secure. It is not right. The farther from the coast, the more difficult it should be. In the depth of the map there should be more dangerous and strong opponents. Changed zombies that move faster and can kill you with 2-3 blows, as well as zombies are animals - wolves or bears. Changed zombies should not aimlessly walk like ordinary zombies but rather resemble predatory animals and sit in ambush waiting for the player to come closer to rush at him. As long as they do not attack, they must be noiseless and when they attack they must make a sound in order to give the player a chance to kill them. It is necessary that there was a feeling that they are preying on you and not you on them.
3) On some private servers have added infected zones and you need to collect a protective suit to go there. This would be a good addition to the new zombies and animals that I wrote.
4) At some military bases, you can add underground warehouses and bunkers inside of which would have sat modified zombies who would see in the dark and try to ambush players.