Plenty of new updates to Zombox
over the last couple of weeks.
The zombie AI system was completely re-hauled. Instead of having perfect knowledge of the player's whereabouts, zombie intelligence is now sight/sound based. Zombies won't attack targets unless they can see them, and will wander towards nearby sounds. This means you can do things like distract zombies with sound while heading in an opposite direction, or sneak up on zombies from behind. Zombies will also try to break down the doors of a building if they feel there is a viable target inside.
Zombie swarming was also greatly improved to prevent pesky zombie-to-zombie, zombie-to-player and zombie-to-prop intersections.
Other improvements to the game involve preventing weapons from being able to hit zombies/props through walls, and adding an in-icon ammo counter for active items.
Here are some .gifs showcasing some of the above changes to the game. The first two animated .gifs show zombies chasing the player and breaking down the doors of the building the player is inside. The third .gif shows some of the improved swarming (sped up to 200%), and the fourth .gif shows the active item ammo counters (as well as what happens to the icon when the player runs out of ammo).