Holopoint

This was a seasonal achievement that was patched into the game december 2016, then patched out, then patched back in december 2017, then patched out again. The devs did not continue updating the game and did not patch it in for either 2018 or 2019.

Obtainable using this depot from december 2017:
appid 457960 depotid 457961 manifestid 4617163804105031229

This version has the option to start the winter raid, complete by exploring each node and killing all enemies until you reach the boss room -- should be pretty straightforward but is rather difficult so save this for last once you are practiced with the mechanics.