SAS Zombie Assault Tower Defense

 SAS: Zombie Assault Tower Defense  is a tower defense game set in the SAS universe. In the game you play as an SAS squad commander tasked with destroying the oncoming zombie horde while civilians are being evacuated from nearby refugee camps. You are given access to automated turrets, SAS Soldiers, and other supplies, all of which can be upgraded to higher levels of zombie destruction.

On a blog published on November 21st, 2014, Aaron stated that SAS TD would not be receiving any more updates.

Turrets
Automated Turrets are wonderful for both killing zombies and making paths. There are three base turrets in the game.
 * Vickers Turret: A heavy machine gun turret able to keep up a steady stream of bullets.
 * MGL Turret: An automated grenade launcher capable of knocking out large groups of zombies.
 * Special Turret: It’s a lightning machine, it’s an acid gun, it’s a flamethrower, it’s all your worst nightmares in one upgradeable turret.

SAS Soldiers
SAS Soldiers are great at finishing off anything still moving after your turrets are done, but because they are still live humans, they will be targeted by all zombies passing by. To increase their survivability, place them on rooftops or other high places that zombies can’t get to.
 * Machine Gun SAS: Much like the Vicker Turret, these soldiers are great at keeping up a never-ending onslaught of zombie re-death.
 * Sniper SAS: By far the longest ranged unit on the battlefield, these soldiers are great at picking off the stragglers or killing the bigger zombies that your turrets are having a hard time with.

Others
Sometime even a wall of guns won’t cut it.
 * Sandbag: Walls that are great for making paths. Use them to make kill-boxes for your turrets or merely to send zombies far out of the way so your turrets can kill them at leisure.
 * Barbed Wire: Able to rip the dead flesh right off the zombies' dead bones. Sometimes able to kill zombies before they even reach your guns.
 * Frag Grenade: Great for killing anything that gets past the range of your guns or for killing everything before it gets to your guns.

Premium Items
Premium items are bought using SAS Dollars or found in support crates sent every five waves. These items can turn the tide of battle when the going gets rough.
 * Cryo Grenades: Liquid oxygen in a bottle...er... grenade. It can freeze smaller zombies to the ground and will slow bigger zombies to a crawl.
 * Incendiary Grenades: Thermite grenades will burn any zombie to a crisp that manages to survive the initial blast.
 * Necro Grenades: The most powerful grenade ever. One of these can kill anything up to Devastators.
 * Mines: Set and forget. These are great at killing any zombies that made it past your defense.
 * Repair Kits: Need your guns back online, like now? These will repair all turrets and heal all wounded in a small area.
 * Longbow Support: This helicopter has miniguns and rocket launchers and will stick around for several waves. Can be a lifesaver if called at the right time.
 * Typhoon Bomber: The Royal Air Force is here to help. Four bombers will drop a steady stream of explosives in a direct line.
 * Necro Nuke: The pinnacle of zombie killing. It explodes and kills anything in its blast radius, then leaves a cloud of anti-necrotic fumes, further killing anything that comes near. It does massive damage to the Ruin instead of killing it instantly.

Zombie Glossary
The zombie horde is vast and varied, but they all have one common goal: to kill the citizens you protect. New additions include a stronger version of the Swarm Zombie and Sprinter, and the Ruin.
 * Swarm Zombie: The most common zombie you will encounter and the weakest. In the game files, it is called 'Schoolboy'.
 * Schoolboy V2: A stronger version of the Swarm Zombie. It begins appearing on wave 6. Named in the game files.
 * Sprinter: A much faster version of the Swarmer, but even weaker. Starts appearing at wave 3.
 * Runner V2: A stronger version of the Sprinter. Begins appearing on wave 9. Named in the game files.
 * Bloater: A giant zombie that will tear down walls and attack turrets just for the heck of it. What’s worse is that when you kill it several worms will erupt from its stomach. Starts appearing at wave 10.
 * Worm: Weak but fast, several of these will emerge from dead Bloaters.
 * Shadow: A moderate health zombie, these are remarkable because they can just walk through your turrets and walls like they aren’t there. Be careful because they move fast and can be at the end of your lines before you can spot them. Starts appearing at wave 15.
 * Mamushka: It's huge and has lots of health, and when it dies it splits into two more zombies, and when they die they split into two more zombies. Just a couple of these guys can turn into a swarm. Starts appearing at wave 17. In the game files, it is called 'Babushka'
 * Robot Clowns: These guys will explode on death and will destroy walls and turrets if you aren’t careful. They also have moderately high health so make sure that your turrets are high level.
 * Devastator: A giant zombie with tons of health, it is able to summon a skeletal horde and create a destructive aura that can kill turrets, walls, and even soldiers on high ground in a small area. Be careful because they won’t go down easy. When killed, the Devastator lets out a high pitched scream combined with a burping sound. Starts appearing at wave 25.
 * Skeletons: The minions of the Devastator, these moderate health zombies will attack walls and turrets.
 * Ruin: The biggest and strongest zombie in the game, the ruin has LOTS of health. It will also send out four fiery tendrils occasionally that can knock down turrets and soldiers as well as anything on high ground. Not to be taken lightly. It takes 4 Necro nukes to bring it down. When killed, the Ruin lets out a loud growl. Starts appearing at wave 40. It then appears 10 waves after that, then 5, then on every wave. In the game files, it is simply called 'Boss'.

Battlefields
There are 8 levels in this game:
 * Mean Street: "This narrow and dark street is a good place to ambush the zombies, you should also be able to get some men onto the rooftops to keep them safe."
 * Sub-Zero: "The zombies have tracked down this human refuge camp in the mountains. It should have been safe, but it isn't. Luckily it should be easily defended... for a while."
 * Dead Warehouse: "Stop the zombies from getting through this cramped warehouse to the exit, funnel them in, trap them, and destroy them."
 * Shop Til You Drop: "Fighting in the open is normally a poor choice when outnumbered, but this time we have no alternative. Use turrets and sandbags to guide the zombies into killzones of your own design."
 * Killtop: "We are at risk of being surrounded, the Zombies will come from multiple directions through this vegetated hilltop. Choose your positions carefully."
 * Touchdown: "Chaos ensued after zombies invaded the stadium. The surviving people have exited but we need to hold off zombies here so they don't spread to the suburbs."
 * Cleanup On Aisle 13: "Zombies are swarming into the department store from the western wall - stop them from getting past you and into the mall at all cost"
 * Outbreak Mansion: "Use the natural choke points to set up a killing field and defend this high priority position. If things go south, well, let's just say that there won't be any point in extracting you."

Trivia

 * The Butcher is called "Bloater" in the game. This is also so in SAS: Zombie Assault 4 and SAS: Zombie Assault 3 Mobile.
 * The Devastator is easier to kill than in SAS 3, however, it has a green aura attack that smacks your towers quickly!
 * All maps within Zombie Assault Tower Defense can only be finished after killing a boss enemy called the Ruin on the last required wave. This enemy is identified as an inflamed demon and also is 3x larger than a Devastator.
 * In SAS: TD, finishing a map will result in a zombie slept in the ground, but later getting squished by a SAS soldier, as well as the "VICTORY" text and your reward will be given.
 * The Choker is the only SAS3 enemy not to return in this game.