Do not complete any EZIC tasks given. The EZIC events that counts as tasks are as follows.

Allowing Mikhail Saratov to enter on Day 11.
Allowing Stepheni Graire to enter on Day 14.
Allowing Marie Escalli to enter on Day 17.
Poisoning Khaled Istom on Day 20.

Confiscating Kordon Kallo's passport, letting him in, and giving his passport to an EZIC agent on Day 27. Then, on Day 31, neutralize both EZIC attackers and do not escape to Obristan afterwards. The day after you will take part in the audit, and its results may only show minor infractions. You will then earn the achievement and view ending 20, which will give you the unlock code for Endless mode.