I've been sifting through the information so far and am ready to post what I believe is going on. This is just me with wild speculation, you may find better information. This is just what I think went on.
Random Enkounters 2017 thread is made on September 30, 2017. If you take the first letter of each sentence, you find the secret message "SECRET MISSION HIDDEN WITHIN". Unfortunately, it is missed because nobody is looking for it. It is hidden in plain sight. I believe the message does not mean hidden within this thread but hidden within the game and later hidden on the Wurmpedia.
On 13 October 2017, the Wurmpedia page for The Knights of Seris is created with the first chapter. Every 7 days, another chapter is added and the lore is complete on 1 December 2017. I believe a lot of the trivia in the random enkounters was pointing to the backstory of Wurm, perhaps in hopes people searching for it wound find the lore page. Here are some interesting lines from the Enkounters:
13 October 2017 - "Today's Random Enkounter is brought to you by the moon Jackal. (I'm watching you!)" - Always watching.
15 October 2017 - "Today's Enkounter is brought to you by Sol - Shining a light on you since 979 NT!" - An important date.
27 October 2017 - "By the NT calendar when did the Gateways to the new lands of Wurm open. He answered correctly! Could you?" - If you can't, you can look it up.
16 November 2017 - "The first challenge was to tell me how many moons were currently in Wurm. He passed that challenge with flying colors... with a little help from the wiki..." - It's all about the wiki.
I believe the thread was trying to point people to looking at the wiki. That didn't work. Nobody saw the secret message or the lore page. It is kept hidden.
April fools 2018. Enki creates the post and asks users to read carefully. Many eagle-eyed readers, myself included, would have noticed the random italicised letters in the post. A quick check reveals these letters spell out "APRIL FOOLS". I'm sure everybody just assumed this was the reason we had to read carefully. It was not.
Taking the first letter of sentence, you find the secret message "I HID SOMETHING WITHIN FIRST SECRET CLUE IN FORUM CAN YOU FIND THE TREASURE".
I believe this one specifically references the forum so you would check Enkis post history and find the secret of the Random Enkounters.
Anniversary rolls around and Enki has had enough. This has gone on for far too long. The users haven't found it. It's time to wake them up.
The secret message of this thread directly references the Knights of Seris. The lore page is found within the hour.
This is the quest. This is the secret mission. We have to find the treasure.
But where do we even go from there? Golden Valley? Gateways? How do we even start the quest? I don't know.
I'm quite fond of the ARG events in gaming communities. I love participating in these even though I'm not that good at it. I know somebody is going to find something which will immediately disprove everything that I've said. This is how this stuff goes. This is all the information that I have right now and I don't know where to go from here.
I also know that people tend to go crazy and overanalyse everything. I'm just throwing out this information because it's important to not get caught up in the little details. I'm convinced the lore page is the key and we just need to figure out what to do with it.