I feel like there is more to mission design than just "do this to get that". There should different kinds of missions for different purpose and different players.
There should be a set of (one time) missions with the goal of introducing the game. A range from basics like killing zombies with different weapns, moving arround the map, using commands or game features, inviting players into group or spending this and that amount of time on a certain server.
There also has to be some sort of weekly questset that is totally worth it. It promotes consistent gameplay and can help to motivate players to switch gamemodes. "Kill 10 different players on rocky, find a potato in colorad, kill 5 supers" Those quests can go from basic to grindy and are just at the purpose of keeping players active and entertained
I would also add some quests that result in achievements. Things that require specific tactics or a certain degree of luck like "killing somebody with a nade" or "killing a player with a nailgun from more than 30 meters" Those quests are close to what big shooters like counterstrike or CoD do and can be easily copied to a certain extent.
Those missions are rather trophies for players to hunt and play for and offer depth to the core community
Last I think there should be temporary or event based quests. You can find a contract or a quest-nps randomly pops up like an airdrop. Maybe everybody on the server automatically gets assigned a quest and whoever finishes it first gets the amazing reward. Those quests are limited in time and offer action packed gameplay
You find a contract thats says "Gain at least XY experience during the next 15 minutes" or "loot an item box within 10 minutes" Those quests instantly put you unter pressure and there is a chance of failure, hence the rewards can be bigger. Those contracts might be optional to be bought in the store which offers a great advantage as you can prepare
quest-npcs can have nice possibilities as well. Like an average joe NPC pops up at ridgeway and asks you to keep a certain area free of zombies or to bring him this and that item. people will rush there, pvp and competition happens
global quests are cool as well. It is a race for the reward and people compete for it. "Go and be the first to kill 30 zombies" is a dull quest, but when you have to be faster than the server it can actually be fun. The options are huge with this one and i can see a lot of things working.
"Conquer the campos clan territory" is a good example. In the beginning its first come first serve, but eventually a fight over tha flag breaks out. More and more people join in and in the end its a big fight. The longer the mission runs, the more people try and die, the bigger the rewards could get. I mean that would be an artificial pvp fiesta extravaganza
Just a few quick thoughts of mine,
A detailed list is really time consuming