Friday, November 30, 2007

Triple Cross Defense

After managing to kill everything at the Desktop Tower Defense, I was trying to be scientific to get higher scores. I used the Flying Boss at the easy and normal modes for measuring the effectiveness of the towers, when only one defense tower is present. You need a strong boss to survive after the assault so you can measure the residue health points.

The main deduction is the firing rate which isn't disclosed in the game. It confirms that the Swarm towers are much more effective than the Squirt towers. And that it's always much more cost efficient to upgrade than to duplicate one. And since Swarm towers are for air defense only, we have to have a mixed defense with Sw towers. Though I manage to kill all flying creeps with Sq towers only except for the Flying Bosses.

Looking at the range data explains a lot of things. Why the DNA2 defense is so effective with a Bash tower inside, but doesn't work that well when putting other things inside, or to join the basic unit into larger chains. It confirms what I have been doing is right, wrapping the creep's path around Sq towers, which seemed to be in conflict with the square defense.

Trying to force the creeps around your tower for as long as possible, the basic pattern is a cross build from squares, with your tower in the middle. You try to block the creeps to run around your cross. For maximum range of an Sq (90), the size of a cross is 5 squares in width. For short range weapons such as Bash towers (50), the cross degenerates into a single square, which explains the effectiveness of the square defense. For long ranges, variations of the cross maze are possible, as long as the creeps are forced to run around the circle within range.

Frost towers are the big surprise. They slows down the creeps from a factor of 0.85 to 0.6. So for $200, you can increase the damage of a tower by 1/0.6, or 66%. This is in a way much cheaper than a Boost tower, which cost $500 for 50%. Though they work differently. The frost towers slow down the creeps that pass through, while the Bo's increases the damage of the towers touching them.

Before building the most effective maze, we need to know what weapons are needed and how many of them. Oh yes, it's hen and egg, as the maze determines the total damage that a tower inflicts on the creeps.

Anyway the Flying bosses are one of the most difficult to kill. It turns out that you need 4 Sw6 (Swarm tower level 6, or Storm tower) and 4 Sq6 with Fr6. You can have more Sw and less Sq but the Sq are shared with ground defense. With Boost towers, it's never worthwhile to build more than two towers. So all you need is two Sw6 and two Sq6, all touching two Bo5 (50% boost). Fr6 has the same range as Sw6, so you probably need two Fr6 to cover the two Sw6's, ensuring a consistent 0.6 air speed reduction.

Spawn creeps are the most difficult to kill land creeps. When you kill one, two little spawn creeps are born with half the strength each. So the Spawns are effectively twice as strong as any others in the same level. It also means that you can not kill them with a short range weapon no matter how strong.

So the defense is based on three crosses, one for Ba (which degenerates into a square), and two for the two Sq, which are sufficient for land defense as well as air. You can do without Ba's but since they splashes (killing everyone within range), I think it's the key to high score by sending in creeps earlier. I doubt if you can do without Sq's because given enough time with a proper cross, it provides the most damage per unit cost.

So the basic strategy is for the Ba to at least kill the first generation Spawns, and then the other Sq's take over. Each Ba can deliver three blows when creeps (speed factor 1) are forced to run along it on all 4 sides. The upgrade sequence is something like this, the first is the level number which are spawns.

6 sq3
13 ba1 sq4 sw2
20 ba3 sq5 sw3
27 ba4 sq6 sw4
34 ba5 sq6 sq5 sw5
41 ba6 sq6x2 sw6
48 all +80% fr6
55 ba6 sq6x2 sw6x2 +100% fr6x2

Initially you have to merge a square, as in the DNA 2 defense earlier, with a small cross 3 square wide. Any larger you are wasting resources and wouldn't survive the attacks. When you reach sq6 you have to knock down the borders and enlarge the cross to 5 square wide if possible. When you have two sq you merge the two crosses together side by side overlapping. The total range are halved due to overlapping, but the fire power is doubled there. This also allows mounting space for touching Bo's and Sw's. The first Sw must be in the dead center of the desktop where the Flying bosses pass through.

The other way to force creeps running around your guns is to sell a Pellet tower to open up some 2nd passage and block the 1st passage. It's no fun as it's increasing slow to sell towers. You might save time by having three or more openings so one is open, one is closed and the other is being sold. But I don't think it's the road to high score, which needs a high kill rate. My strategy kill everything without selling and juggling except for the 2nd last Morph Bosses. You may go to the scoreboard to see my humble scores - theplayer, and there is a group score with me in it - players.

Now perhaps when there's nothing to discover, I might go back to my real desktop, top score or not.

Thursday, November 15, 2007

Desktop Tower Defender

I stumbled upon this game and I was addicted. This is the winning strategy.

If you like Ages of the Empire but have no patient, this is for you. There are sufficient variations to apply your warfare theories but the rules are limited so the game can be defeated with not too much practice and research. So, it won't last forever, and you will be back to your real desktop very soon.

The weapons:

The Pellet tower is like Napoleon's foot soldiers. They can hold their lines well, their fire power is decent, but they fire too slow. You needs lot of them. Although their damage/cost is good, the (rate of damage) / cost is poor compared to the Squirt Tower which fires much more rapidly. They do not worth upgrading for more damages. However, like pawns in chess, they are very important. They are cheap, they are plenty, they are disposable.

The Squirt Tower is like machine guns or cannons. The rate of damage / cost is best as they fire non-stop. This is the main weapon of choice.

The Bash Tower is like a land mine redeployed in a short time after every explosion. Or it's like a fixed cannon. It has the best damage/cost ratio. It fires very slow but it damages enemies all around it. It's complements the Squirt Tower.

The Swarm Tower is like anti-aircraft artillery. It fires 4 missiles at the same time. It's a little slower than the Squirt Tower, which is for air and ground, while the Swarm Tower is for air defense only. I'm sure this is necessary. In the beginning, Pe and Sq are good at defending the first wave. When all the weapons are upgraded, the Sq seems to be increasing effective. There is a strange value for the last upgrade. It is apparent that it's better to build another tower than paying for the final upgrade. Anyway, one tower is about enough to kill off all aircrafts, except for the flying BOSS, which are almost impossible to kill. But I'm getting there.

All other weapons are not worth it. They do not have sufficient damage at the final upgrade. Just the Sq and Ba can get the job done. The dart tower is pretty good at the Groups but redundant when you fire power increases. I still don't find the Ink Tower effective against anything. The Snap Tower is just too weak for the big Bosses.

One useful piece is the Frost Tower, which slows your enemy down.

The Boost Tower is only useful if you have several towers placed around it. It's may be useful in the final stages when you have a lot of money and a lot of weapons. For example, it only make sense if you have three Sw towers put together to use Bo. Otherwise it's better to buy another one.

The basic strategy is to slow your enemy down to absorb fire. It's the classic square formations to defend against cavalry charge. For the desktop, I came up with the DNA2 defense based on this formation of Pe's. Obviously Pe's are used because they are the cheapest. You replace some Pe's with other weapons, and put others around it.

I think it's the cheapest way to get your enemy run the most, taking fire at all sides, it's also the most compact in terms of area.

Of course you don't use only one. The pattern can be repeated indefinitely, can be packed very closely to fit your desktop defense space. You can rotate it, flip it, to form long strands something like DNA spirals. Typically you shape your strands so you have plenty of spaces in the middle of the desktop for deployment additional weapons, typically air defense.

Actually you don't need anything else but Pe's in the DNA2 formation. You don't need rapid fire Sq because 10 Pe's firing at random is as good as a Sq. However, the Spawn are pretty good at spoiling things. Distributed fire by Pe's cannot deal with Spawns effectively. Every time you kill a big Spawn, you get lots of little Spawns. There's no way to really slow them down and you have to kill them several times. So you need concentrated fire power other than plenty of Pe's.

It should be noted that the Spawns can pass through the gaps some of the times when the squares are barely touching. But when they pass through one formation, they will be caught in the next. Just remember to block those vulnerable corners where the Spawns can escape to their home base. Even for this weakness, the DNA2 is still much more effective when the enemies have to pass on all 4 sides of a middle square.

The deployment:

Basically you block your enemies so they only charge through your square formations. Obviously the first middle square should be a Ba. Then you need a Sq concentrated at the first corner of entry. The position is crucial. If you put it on a middle square it performs poorly. It shoots everywhere instead of concentrating on where you need it. It's optional to have a second Sq at the entrance corner of the 2nd DNA formation. Typically Spawns pass through the 1st formation will be killed in the 2nd.

The upgrade strategy:

A few of the DNA formation can kill most enemies, with just a Ba and two Sq's. You want the most concentrated fire power. So you upgrade the Ba and the Sq on the same first DNA formation as soon as you can. The 2nd Sq should be one or two upgrades behind. I think on the final upgrade, the Sq are more effective with rapid fire, but of course the Ba's damage is impressive. If you survive the initial assaults, it doesn't really matter you upgrade the Ba or Sq first, as long as you don't upgrade all two Sq first. Save some money for the Ba.

Also you need to upgrade the Sw's regularly for each air assault. When you reach the final upgrade, you should buy yourself another Sw just short or the final upgrade. But I'm not sure the final upgrade is useful. It looks like it's better to have two instead of going for the final upgrade.


With the simple strategies you can kill most enemies except for two types of Bosses, the Morph Bosses and the Flying Bosses. Some other bosses are pretty hard to kill too. With mobility, you can certainly kill everything on the ground.

You can trap your enemies within your DNA2 formations by blocking and unblocking exits. They just run around absorbing fire. Therefore only one Ba and one Sq or two will be sufficient.

For mobility to work, you need two strands of formation. When you block one all the enemies have to go back for the opening in the 2nd strand. Timing is very important because unblocking becomes increasingly slow. You want to keep all enemies running pass your Ba again and again. You need very long strands, with 6 or more middle squares each. So you have plenty of time to unblock and block your exits.

Ultimate defense:

I can kill everything except for the flying bosses, which you cannot slow down. With 4 final upgraded Sw I manage to kill 2/3 of a flying boss. So I'm close. I'm not sure Sw is the way to go. Super guns in form of Sq are pretty good. The Bo's are pretty effective and money saving when you have a bunch of Sw and Sq trying to shoot down the flying bosses.

I have no idea how the other defenders defend. I looked at the top score once and the winning pattern is rather misleading. The person could be hiding his tracks in the final stage by selling things and buying things not needed.

I'm sure there are totally different strategies. I rather not look at them because it's part of the fun. I prefer my style, more like a warfare strategy game than shoot them down types.

Tuesday, November 6, 2007

Google blogroll released

Of course it only make sense to generate blogrolls within Google reader - you list the blogs you read in your reader. Google reader has clips to allow you to list the feed items, but not just the source as in a blogroll. Now the Google blogroll is a slight modification of the clips, in turn is just some particular display of a feed.

I have already done a very flexible feed displayer a couple of months ago. One use of it is for blogrolls generated from Google reader. It's a lot more flexible because it's a client side script, it's a couple of months ahead too.