Most effective path (tower defense maps)

I'm playing a SC2 "tower-defense"-like map, and need to find out how to build walls efficiently, so that units stay longer on the map and take more damage.

The map looks like this:

The most common strategy is to build your wall around a turning point (the red arrow). This seems to give you the ability to deal a lot of damage and a decent time advantage.

But how can I increase that time, by building two spirals, around two turning points, and make it so the unit has to pass one of them 2 times in order to get to the end?

I know it's possible, I've seen it in another map, but can't remember how. :(

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please specify the map you're talking about. Some theory: sometimes it's possible to trick monsters by creating 2 paths - long and short. When monsters are going by short one - close it. And wait some time. Then open. Repeat FTW! – Meta Oct 8 '11 at 15:40
"Gem Tower Defense", "tc's Power Towers", probably others.. – Alex Oct 8 '11 at 15:47
possible duplicate of Optimum Mazing Path (by Length) – bwarner Oct 28 '11 at 12:42
@bwarner its not the same problem, in the one you linked to you are doing path in a simple A->B path, in this question your have multiple points in pathing so you have some other options for optimal build forcing the creeps to take the same path multiple times. – Blem Oct 28 '11 at 12:55
@Alex: If you are still looking for efficient solutions, I've posted the tactic I've used a several times. I don't think there are better ones available. Most people however want to have the fun of figuring it out their-selves. Even when using such a solution as posted here, your points will still matter dependent on which towers you get and which you choose to combine... – Tom Wijsman Dec 24 '11 at 17:28

Create a 6-pass spiral in the middle, place most towers in the middle

You should not go for long lines as the time the towers can fire at creepers won't be long, which gives you a non-optimal build. A six-pass build is none-the-less a good thing, but an optimization to it is that you make a spiral near the center (where the roads cross).

This way, the monsters will go through the spiral several times and the (special) towers in the middle will do optimal damage to the creepers that pass through. Passing through the whole surface of a tower rather than running through it with a line is obviously more efficient.

There is a 8-part video where this tactic is used to beat ABSURD mode:

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The best solution i have found for games like this where you can manipulate the path is to build a wall that divides every other turn point on each side, block the wall in 1 side and build strong towers in the open end.

The green line is cheap towers for walling and the blue line are your expensive damage and utility towers for doing the actual damage, this forces the creepers to pass your expensive high damage towers for every turn point. remember to focus the high damage towers right at the path if the game has flying units you want all your towers to be able to reach them. if the game has some anti air towers and you need to build some of them you can have them as part of the green wall where the path crosses it self.

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This is a very bad solution, note how the time the creepers are near the towers is very low. Besides going for a six pass you'll want to optimize the time creepers are within the range of a tower. – Tom Wijsman Dec 24 '11 at 17:17
This kind of build forces the creepers to pass the area of the blue lines every time they need to go to the next point, forcing them to pass that area 8 times. – Blem Sep 22 '13 at 14:44

I realize this is a bit of a necro, but I found this page looking for some tips myself.

2 things, the spiral is much better, for maximizing the time mobs spend near damage towers.

2nd, the 8 pass alternative does NOT work, as only 1 edge of the map is actually impassable, in the proposed picture, the mobs will walk underneath the blue, not through it as the TD was designed poorly.

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