Valve has not given the green light to the Classic Offensive project, which was supposed to revive Counter-Strike 1.6

The Classic Offensive mod development team, which sought to recreate Counter-Strike 1.6, received unpleasant news: Valve refused to release their project on Steam after eight years of work.
Here's What We Know
The Classic Offensive developers reported in December that they submitted their mod for review in October 2024, but did not receive a response within the usual processing time of three to five business days.
And in January 2025, the team released a statement saying that Valve had "removed their app" without any explanation. One can only imagine what a hard blow this was, as the team had been working on the project for eight years.
Classic Offensive was approved through the Steam Greenlight programme in 2017, and its leader ZooL started experimenting with CS:GO mods back in 2015. The mod was positioned as a renaissance of CS 1.6 using the modern Source engine. The developers assured that they did not use the Source engine's cracked code and kept in touch with Valve representatives.
So, if you really wanted to play a CS 1.6 "remake", it won't happen in the near future. Unless some miracle happens and Valve reconsiders its decision.
Source: @csco_dev