One of the biggest dings against NZA for most people was the lack of a drop-in/drop-out coop system, so you always had to pull together 2-4 people ahead of time and go in together. Looks like the latest patch from Rebellion has added that option, plus a bunch of other stuff. I took a break from the game to go play other stuff, but I think I'm going to jump back in now and see if the new changes will bring people back in to play more.

From their forum post on Stream:

Update 1.05 Now available!Sniper Elite: Nazi Zombie Army ups the ante with Spring updates

Two major new features added in less than a month based on player feedback

Independent UK developer Rebellion has today released update 1.05 for co-op survival shooter Sniper Elite: Nazi Zombie Army, not only enabling co-op players to multiply the numbers of enemies they face, but also adding support for drop in / drop out functionality.

Hot on the heels of April’s popular ‘Multiplier’ update - allowing solo-players to multiply the numbers of enemies they face to terrifying levels - this update is the second major feature added to the game in less than a month based on suggestions and comments from the game’s growing community.

Update 1.05 also includes a small selection of fixes.

Key Features:

Drop in / Drop out functionality added. (See technical notes below)

Co-op enemy multiplier added. (e.g 2 players can play against 4 player numbers of enemies)

Fix list:

Fix for potential progression blocker on Cathedral level.

Fix for progression blocker on Library Of Evil.

Fix to make sure Bullet cam "minimal" settings reduces bullet cameras in game.

Fix to stop score points exploit on skeletons.

Known issues:

Some single player inter level saves will be invalidated with this update. This was due to level progression fixes. If problems are encountered a level restart may be required.

Technical notes on drop in /drop out:

- Can only join whilst players are in lobby or in actual gameplay.

- Cannot join whilst in loading, waiting for players, syncing, cutscenes or end game menus.

- Private match option blocks all joining.

- Quick match can be found and joined by any player unless private match is selected.

- Private game can only be found and joined by friends, either through an invite from host or by selecting to join game from steam in-game overlay, unless private match is selected.

- The private match option can be toggled both in the lobby and in game via the pause menu.

- The private match option is not available when in cutscenes or end game menus.

- Players joining outside safe zones will spawn at the host position.

- If the enemy multiplier is set to default then when a player joins the enemies increase to match the number of players.

- If the enemy multiplier is set to default then when a player leaves the number of enemies will only decrease to match the player numbers when a safe zone is reached.

- Host must wait for players joining a game to be fully in gameplay before being able to restart a game - a message box will popup informing the host of this.