The towers types are common to both DTD and MPDTD and are as follows:
Pellet -> Sniper: Basic towers, usually used to build the walls of a maze. Sniper towers do high damage with the largest range of any tower.
Squirt -> Typhoon: Fast-firing tower which fires at ground and air creeps, though isn't strong enough to handle the most powerful flying creeps.
Dart -> ICBM: Missile-firing tower which damages enemies in a blast area around the initial hit.
Swarm -> Storm: Anti-air tower which only fires at flying creeps.
Frost -> Blizzard: Utility tower which slows creeps. Very cheap to upgrade.
Bash -> Earthquake: Area-of-effect tower with a small radius which does incredible damage.
Ink -> Ink Blot: Unusual tower with a minimum and maximum range which slows and damages creeps.
Snap: One-shot tower which can be destroyed to damage and stun enemies. This tower can be used as a quick (though expensive) way to juggle, and is also one of the only ways to handle super-high-level (90+) flying creeps.
Boost: Increases the damage of all surrounding towers. Best placed at the centre of a square of 8 other towers.
This method is used by most newcomers in the DTD-universe. There are only a few people who really mastered it. You build up your maze, place your main damage towers and upgrade them. If you have your maze you tweak it over and over to get the maximum amount of points out of it.
This is where you place diagonal rows across the middle of the desktop (usually 3) so that the creeps have to go up and down several times. This is probably the best style of normal mazing because it requires so little towers for such a long path. Usually has better upgraded towers in the exact center so it affects flying creeps as well, but spawnlets can skip some of the path when they split
This is where you place your towers so that the creeps have to move in a spiral to the center of the map and then in a spiral out to the exit. Usually the main attack towers are in the middle of the maze, where they have the most effect on Flying creeps.
Be careful however. When using diagonal mazing watch out for the spawn creeps as they can split through gaps between towers.
Many players are switching from the normal mazing to this method, where you build a maze with more than one exit. Then you block one exit with a tower so the creeps are moving to the open one. Before they can get out you sell the blocking towerand block the exit. Now the creeps are turning and try to get to the now free exit. By using this technique you can spend nearly all your money on your defenses against flying creeps and get a high time bonus, because you can send up to 7 waves at one time. A video on juggling can be found here.
In Multiplayer Desktop Tower Defence, up to 10 people can play at one time. Upgraded members can start games with up to ten people (and choose many more options compared to basic members), and non-upgraded people can create games with 5 people.
Unlike the single player game, in which high scores are achieved by containing waves within a large maze (possibly with juggling) and killing them slowly, MPDTD are usually won by the player who can kill creeps faster than their opponents.
This can involve placing towers closer to the entrances than a typical DTD maze; sometimes even separating the maze into two damage zones, one at each entrance.