Dataminer Maksim "Gabe Follower" Poletayev found mentions of various modes in the CS2 files. These included Danger Zone, Escape and VIP (Assassination). They were discovered in the main script file for the Deathmatch mode after the Call To Arms update was released.
Danger Zone is the Battle Royale version of CS created in CS: GO by Valve. Escape and Assassination were originally developed for CS 1.6 by the game community.
Escape had a simple concept. The terrorists had to reach a specific zone. They couldn't buy weapons, but the guns and equipment could be found on the map. Assassination was also known as VIP mode. One of the CTs became the VIP with 200 points of armor and only a single pistol. The goal was to escort him to the rescue zone. T-side had to kill the target.
Call To Arms came out on February 7. The developers brought back the popular Arms Race mode. There are two maps available: Baggage and Shoots, which were reworked for CS2. The complete patch notes are available here.