But fortunately, this update does fix a notorious bug that has existed from the very beginning. Thanks to a fan, I was able to reproduce it. It turns out equipping landmines as the primary weapon would freeze the game going into any mission.
In the future I am a bit tempted to make a Zombie Guard 2, in Unity, with much better special effects, audio, music, and features. Zombie Guard is made in Corona, which these days is a less supported engine that I do not recommend.