How do I access HITMAN 2 Sniper Assassin mode?

Sniper Assassin mode was previously available as an early access pre-order bonus for HITMAN 2.

With the release of HITMAN 2, the Sniper Assassin ‘Himmelstein’ map (the same map from the pre-order bonus) will be available to all players as a brand new game mode within HITMAN 2. However, we’ve made some improvements and tweaks as part of our commitment to supporting our new game modes. To start, we’ve added a matchmaking option (that will launch in a beta state), incorporated a new Performance XP feature that allows you to rank up your player profile, and added achievements/trophies for this game mode. As a result of these changes, progression from the standalone Sniper Assassin will not be carried over into HITMAN 2. Additionally, the standalone version will be shut down on November 13th 2018 and players will need to launch HITMAN 2 to play Sniper Assassin.