This is a short timeline that I summarized based on Entropy Zero 2, original Halflife 2 and its Episodes. This contains a lot Personal Understandings and guessing. Please correct me and/or provide more details
 
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The event prior to EZ2

 
1. Advisor sent a Recon team, including Clone 36, to Arbeit Facility.
 
 
2. Mossman boarded a helicopter from Black Mesa East immediately and flew to Arbeit Komms after saving Eli & Gordon. She then did her researches, recorded everything, and then she arrived at Arbeit Comms.
 
 
Although it is not certain which of the above events will occur first, the timeline might show that the clone was down in the Arbeit/Aperture facility long enough to cause it to be. Therefore, we can assume Evil 36's main goal is to reconfigure the Arbeit Comms and not track down Mossman.
 
 
 

The Journey and the Awakening

 
3. Clone team failed, and Mossman fled. Both factors combined caused the Advisor to activate Main 36.
 
 
Between events 1 and 3, Citadel Teleporter Blew up
 
 
4. Gordon was buried while 36 went through Aperture Tests, Exhumation, and Gordon. Mossman arrives at Arbeit 2, to send her research to the C17 rebels.
 
 
According to Episode 1 and the Emails of Half-life 2, Gordon was buried for a few days before Alyx finds him. Walker has enough time to travel through these areas and reach Arbeit 2(. We also saw at least one day-night cycle).
 
 
5. 36 failed to capture Mossman in Arbeit 2 facility. Mossman escaped, and transmission was stopped and intercepted and retransmitted by the Advisor. It ends up in C17 citadel’s database.
 
 
6. Gordon was found by Alyx, who watched the transmission. 36 went to Arbeit 3 and chased Mossman.
 
 
 

The Final Countdown

7. 36 entered Entropic Control and defeated its clone, while Gordon and Alyx tried to escape C17
 
 
8. 36 survived Entropic Lift Control to anomaly, while Gordon and Alyx witnessed Ruins of Citadel causing a Portal Storm. This storm spread to Entropic Lift Control aswell.
 
 
9. Alyx was injured by a Hunter while fighting the Advisor. Vortigaunts began hunting for Advisors and came to the aid of 36.
 
 
The reason I said the Phenomenal occurred inside Entropic Lift Control is not because of the Anomaly/Borealis, is that, even though you're very close to the Anomaly and the Portal Storm From where you enter, manifests It was not from the Lift that connects to the Anomaly. This means that it took place outside of the Arbeit Anomaly area.
 
 
 

The Omega

 
10. 36 meets G-man. Gordon discovers Antlion Extraction. Vortigaunts began to heal Alyx. G-man was given the opportunity to leave 36 and went to talk to Gordon.
 
 
As stated in the previous chapter, if the portal hurricane is manifested at the Citadel, it will explain why Gman will leave 36 mid-conversation. This also connects the timelines of these two series.

 
 

 
 
Hope you enjoy the Guide about Entropy : Zero 2 – Event Guide & Secrets, if you think we should add extra information or forget something, please let us know via comment below, and we will do our best to fix or update as soon as possible!