It's been a while, so I've decided to add a few more features and fixed a few things.

• The 1st level is now a tutorial which you can skip.
• New controls implemented, such as time control. You can speed up or slow down the game.
• New identifications for units added. Along with the previous 'hover over unit to see what it is', there are now functions to keep the icons on, for units that are already on the level, plus a trail render option. And zombies cough.
• Slight graphic change, as I've modified some materials to not chew as much CPU, as it may have before.
• Updated menu, and ending.

Some things are still somewhat experimental. Such as the rag dolls for when zombies die. 

None of these updates currently apply to the Android version.