Tower Defense

A game where you defend a building from monsters using other buildings, sometimes with a unit or two to back you up. Similar to Multi Mook Melee, Tower Defense games have you facing wave upon wave of "creeps" until a given number reach their goal, or you survive the final wave.

Creeps will move along the path that is either:
 * Fixed, where creeps move along the same paths.
 * Dynamic, where the placement of towers will determine the paths which creeps move along. Usually you can't block the path way completely with your towers. Dynamic paths usually create a strategy called "mazing", placing your towers to create a path that lengthens the amount of time enemies spend near powerful towers before they can reach the exit.

A good Tower Defense game will have:
 * Creeps that behave differently. For example, flying creeps will fly over your towers in Dynamic placement games, allowing them to bypass most of your defenses.
 * "Boss" creeps on certain waves.
 * A strategy that requires a balance of producing more towers and upgrading existing ones. More important in dynamic path type ones.
 * Balance between different towers. Ideally, none of the tower types should be completely useless.

As of lately, a trend in this genre has started to develop where the games will feature the ability for the player to be the attacking force pitted against the towers. Some games in the genre get to the point of devoting themselves entirely to this, eschewing the defense element altogether.

As a Full Game:

 * Antbuster
 * Bloons Tower Defense
 * Bubble Tanks: Tower Defense. An updated version (1.5) can be played here.
 * Comet Crash
 * Create-Your-Own Tower Defense
 * Crush The Castle Tower Defense
 * Cursed Treasure
 * Defenders Quest (with features of a traditional RPG)
 * Defense Grid the Awakening
 * Desktop Tower Defense
 * Dillons Rolling Western (which also mixes in Action elements)
 * Dungeon Defenders
 * Fieldrunners
 * Final Fantasy Crystal Chronicles: My Life as a Darklord
 * Final Fantasy Crystal Defenders
 * Flash Element Tower Defense
 * Fun Orb's Orb Defence
 * Gandalf the Sorcerer for the Commodore 64 may well have been the first ever example of the genre.
 * Gemcraft
 * Gemcraft: Episode Zero
 * Gemcraft Labyrinth
 * Glissaria
 * Grim Grimoire
 * Heroic Armies Marching
 * Immortal Defense
 * Iron Brigade (formerly known as Trenched)
 * Kill The Heroes
 * Kingdom Rush
 * Locks Quest
 * Mini Robot Wars (known as Tiny Defense on the iOS system)
 * Monday Night Combat
 * Mushroom Revolution
 * Ninja Town
 * Onslaught 2
 * Orcs Must Die
 * Patch Con: Defend the Library is a Touhou fan game that has elements of Tower Defense games except characters can move. It also has an actual tower defense mode that plays it straight.
 * Pixel Junk Monsters
 * Plants vs. Zombies
 * Pokémon Tower Defense
 * Rampart
 * Revenge of the Titans
 * Sanctum (With a hybrid of first-person shooter)
 * Savage Moon
 * Sol Survivor
 * Soulcaster
 * South Park Let's Go Tower Defense Play!
 * Stickman Tower Defense
 * System Protocol One
 * Tower Madness
 * Toy Soldiers
 * Unstoppable Gorg
 * Vector Tower Defense
 * Whiteboard Tower Defense

As a Mini Game:

 * Age of Empires II: Age Of Kings (and the expansion pack Conquerors) had a "Wonder Race" game type, in which you are required to build a wonder and defend it for 200 years before your opponent(s).
 * Civilization IV came with a "Civ Defense" mod, in which one starts with a certain number of cities, spends money (rather than the usual "hammers") to add to their fortifications and defenses, and then horde after horde of barbarians come at you.
 * Final Fantasy VI and Final Fantasy VII are probably the Ur Examples:
 * Final Fantasy VI has has an event similar to this halfway through the first part of the game; there's a difference in that you battle the mooks using the standard battle system, but otherwise the execution is the same.
 * The Fort Condor mini-game in Final Fantasy VII is essentially a tower defense game.
 * The Trope Maker was the various user-made defense maps in Starcraft - Sunken D, Turret D, Stack D, etc. The Starcraft editor did not allow you to create new units or buildings, so they usually made much more use of mobile units than most current Tower Defenses. See, for example, this video of Weed D, which is recognizably a fixed-path Tower Defense game except that the "towers" being "built" are Mutalisks.
 * The Trope Codifier was Tower Defense maps for Warcraft III. The editor was much more sophisticated than Starcraft's, allowing for greater variety in attack buildings. Multiple subgenres appeared and proliferated, such as the Wintermaul clones.
 * The expansion pack, Frozen Throne, contains a Tower Defense map as a bonus level.
 * Some user-created maps for other Real Time Strategy games follow this style.
 * The Iron Grip series is part Tower Defense and part FPS.
 * A variation of this appears in Legion's Loyalty Mission in Mass Effect 2, where Mooks must march towards you in a fixed path while you have Legion hack a few turrets around the area to shoot at them.
 * Alternatively, you can just cap them yourself.
 * Three D Dot Game Heroes has a Tower Defense mini-game called Block Defense.
 * Revenge of the Titans is a Tower Defense game that is heavily inspired by 1950's sci-fi.
 * Den Defenses in Assassin's Creed: Revelations.

Tower Defense games that include the ability to play as the attackers:

 * Anomaly Warzone Earth: Considered by many to be the Genre Launcher for Tower Offense games. Here, you upgrade a constantly moving force to attack an enemy base/garrison filled with turrets.
 * Villainous: Also a Tower Offense game where you play as the villain on his quest to take over the lands.
 * Armored Core V: A Mech Game where most of the online component consists of you assaulting other team's territories akin to a glorified 3D-Tower Defense game. As with everything else however, being intercepted by that territory's owner and prepare for a Team Deathmatch style game instead, with all the turrets present. Like real Turret Defense games, turrets run the gamut from "squishy little targets" to "hard as a barnacle to remove", and combinations of turrets often give even the most experienced players trouble.
 * A game literally named Anti-Tower Defense. You select versions of certain robot creeps to casually walk (argh) through a progressively harder tower network.
 * Plants vs. Zombies on the Xbox 360 has the 2-player versus mode. The zombies' side has you attacking the plants and attempting to get into the house, while defending your targets from the plants' attacks.
 * Stronghold, a series of castle-building games which are mostly defensive except for the rare mission where you play an invading army trying to get into an opponent's castle. These also involve setting up a complex supply chain, managing taxes and morale, but for the most part, the aim is to build a big wall around your keep, and stock it with as many archers and crossbowmen as possible to pick off the approaching invaders.
 * Dungeon Defenders has an event match called 'assault' where, "in an unexpected twist, YOU have to attack THEIR crystal!"
 * Pokémon Tower Defense also features sections where your 'Mons go on the attack.
 * Doggnation was originally designed as a Tower Defense game, but this eventually changed into more of a puzzle game where you have to help the "Doggs" carry specific blocks to upgrade their castle.
 * Dead Space Ignition has a Hacking Minigame that is a tower Offense game. You send out an unlimited number of computer viruses to break down the computer firewalls and get to the computer program before time runs out.
 * Game Mod Red Alert 3 Paradox is unique in that it has BOTH sides of a tower defense game as RTS factions.
 * Defenders of Ardania, a Tower Defense game set in the Majesty universe, has you do defense with towers and offense with units at the same time.