Flash TD: Analysis

By Shamus Posted Tuesday Jan 16, 2007

Filed under: Game Reviews 17 comments

This is getting unhealthy, but here is some more in-depth stuff on the game:

Most of my strategy from yesterday was based on intuition. I decided to run some tests and see if I could prove what I’d been thinking. The very first level is great for running these kinds of tests, so I played the first level several times with differing tower configurations.

This seems like a good place for a tower:


It covers the entrance, the exit, and part of the middle. However, the way towers work is that they always aim at the guy in front. The tower deals 6 damage, and each sheep has 10hp, meaning you need to nail everyone twice. The tower Starts nailing each sheep once as they come in the door, but they move out of range too fast for it to get the second hit.

Then they come back into range from below. It turns its attention from the entry point and begins zapping the sheep at the head of the line for a second time. It’s killing them, sure, but they are moving by just a little faster than it can shoot. Meanwhile, more are coming in the door which have not been shot at all, and are still at full health. Because the tower is focused on the head of the line, one or two sheep manage to slip by this tower unscathed.

Then as they approach the exit – passing the tower for the third time – we have about half of the sheep left, which have all been hit once, and one or two sheep which have not been hit at all. Those uninjured sheep need 2 hits, and the tower can’t bring them down quick enough before they make it off the edge of the board.


But placing a tower here works. As they walk by the first time, it cleanly destroys the first third or so of the sheep, and leaves the rest with exactly 1 hit. Nobody gets by unharmed. Then they come back around for the second pass, and the tower is able to finish them off without missing anyone.

So, I played the first level through several times, using just one tower. The image below shows how many sheep got by with the tower in the given position:


As I suspected, the towers on the right did much better. What really surprised me was how poorly the towers on the left did.

UPDATE: I wrote this post early this morning, and as of right now the author has messed around with the game again. The sheep move just a little faster now, so you won’t get the results I describe above. However, a tower placed in the location indicated in the second picture will still clear level 1 all by itself.

Now, this is only true because the line is long and moves just a tiny bit faster than the tower can fire. Even when it is killing sheep, each one dies a step closer to the exit than the previous one.

There are a few “BOSS” levels, where you have just one creep which has a whole bunch of hitpoints. However, the first boss is several levels in, so there is no good way to experiment with it repeatedly. So, I can’t really test how towers work in these situations. It’s also tough to get an accurate reading for the BOSS hitpoints, which means measuring performance becomes difficult.

In any case, I speculate that when pounding on a single boss, the tower performance is directly linked to how much path area the tower covers. In these cases, I think my bottom tower which let an abyssmal 12 sheep slip by might actually perform the best. Very little of its coverage area is wasted, since it is nearly surrounded by path.

The second level is interesting because the creeps have 42hp. Towers do 6 damage by default, so we need to nail each sheep 7 times. This means that even if we put our towers on the right where they will do the most good, three towers will not be enough. We would need 4 towers, and some of their potential will be wasted, since we could deliver 8 hits to each sheep if we needed to.

Each tower costs 7g, and delivers 6 damage. For 13g more, you can upgrade a tower to do 16 damage. For another 32, you can upgrade to 39 damage. Now, this would be overkill at this point in the game, and it would very nearly drive us broke here at level 2, but let’s look at what we get for our money:

Tower Level 1: 6dmg / 7g = 0.85 damage per gold
Tower Level 2: 16dmg / 20g = 0.8 dpg
Tower Level 3: 39dmg / 52g = 0.75 dpg

Contrary to the advice I’ve read elsewhere, it looks like you get less for your money by doing upgrades. This seems a little counter-intuitive to me, but there it is. Each upgrade gives the tower a small boost to its range, which is hard to evaluate.

In any case, here in the early stages of the game our goal is to deliver 42 points of damage to each creep without going too far over, thus wasting money.

Without upgrades, we will need 4 towers, with a total cost of 28g. These towers will do 24 damage, so if they hit everyone twice it will overkill our poor 42hp creeps.

If we build 2 towers and upgrade one of them, our total cost is 27g. The towers will do 22 damage. We’re no longer overkilling, but we only saved one gold. That’s no good. Its also better to have more towers, because if they are spread out enough you can avoid overkilling the lead guy in future levels.


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17 thoughts on “Flash TD: Analysis

  1. Kris says:

    I missed out. I haven’t been able to finish the first level without using two level 1 towers, or one level 2.

    I’ll keep working on it… Damn you for getting me addicted though!

  2. Bogan the Mighty says:

    Now those are results on just archer towers aren’t they? I think upgrading cannons can be a little more productive. If you get the rocket tower which is more overkill than its really worth it effectively doubles damage at double price assuming they shoot twice as fast like it claims.

  3. Nick says:

    Just so you know, there’s a strategy that was posted posted based on the current build (Found it in the Flash Element TD forums). I just did a quick run through with that strategy, though you have to deviate from it at around level 34, I still managed to slaughter the last level and ended up with 39,679 points. Not bad.

    I do find it a nice thing that the tweaking being done by the creator might eventually make that particular strategy ineffective (or maybe even more effective).

  4. Robert says:

    The right side is definitely the place to put towers.

    I’ve done very well with the following path:

    1st level: 1 base cannon tower on the right-hand side
    2nd level: bump it one upgrade
    3rd: bump it to max
    4th: no change
    5th: add 2nd cannon
    6th: bump it one
    7th: bump it to max
    use your wood to research fire towers – you won’t be building anything but fire towers until the very end game
    8th level (first flyers): add 1 fire tower on the right side.
    9-14: upgrade that fire tower SLOWLY – save your money.

    Don’t upgrade or add towers until a significant group manages to get past the fire zone’s left side – upgrade it before they come around to the other side, if necessary.

    Use your second wood after level 14, 21 and 28 to increase interest to 15%

    Add/upgrade fire towers as slowly as possible. Until you’re in the mid-20s, you will not need to add many towers – four or five is plenty if they’re placed in the right-hand sweet spot. You should be able to save at least 10 or 20 thousand gold up.

    For your very last upgrade, at level 35, research water towers and place one to slow down the creeps as they come into the death zone. You’ll still only have a handful of fire towers until the high 30s – then you’ll need LOTS of them.

    Mass fire towers seem to do better against the late hordes than rocket towers; that 2000 damage is awesome but it has no splash, and to get the rockets you have to blow all your upgrades on elemental towers. Far better to get the interest and use the money to buy more fire.

    Fire is cool. Heh heh.

  5. Myxx says:

    Sheesh… I’m not sure I needed to become even less productive at work.

  6. Malkara says:

    Rofl. I’m like 149 atm. in the final few levels, I ended up just having to literally fill every available space with fully upgraded cannons.
    Then I had to like constantly press the life button as those 25000 health monstrosities moved through.

  7. Russ says:

    As far as gauging the Boss’s Hitpoints, you do know that Spacebar shows a HP meter on the creeps…it may only work on High Quality.

  8. Russ says:

    Actually, on the Jan 17 update, he has added that Creep Health can be seen with “H” or Spacebar.

  9. Kayle says:

    While the arrows shoot faster, the splash damage with the canon is significant and appears to make the canons noticably superior overall, except for air levels.

    The strategy I’ve been using is to use canons, sell them before an air level, take the interest upgrade for every upgrade until level 35 where you do fire research and start using fire towers instead of canon. By being very parsiminous with the number of towers and upgrades (I don’t need more than 3 towers until level 17, except for the level 11 boss), you should be making huge amounts on interest by the higher levels and rack up points.

  10. Griffin says:

    I hit 130K or so by researching only interest and building nothing but cannons. I agree that the splash damage makes them stronger (although less all-purpose) than the arrows. They even get the job done on the final levels, although you have to buy lots of lives as the creeps take laps. So it’s definitely less humiliating to use fire towers as you can actually win on the first lap. =)

    The reason there are so many people on the leaderboard dead on level 39? It’s on purpose. You don’t get interest after 39, so if you’re going to have to buy a lot of extra lives to make it through (as I did), you should just let yourself die.

    If your goal is points, that is. I find it much more fun to play a “normal” game — research and use all towers — even though I can’t score over 20-30K points that way.

    It’s a very fun little game, although I have to think that the balance breaks down towards the end in that it’s not hard to get literally more money than you can spend.

  11. Craig Moynes says:

    Hey Shamus, did you see this video: http://www.youtube.com/watch?v=jU4KOT9J4ck

    It’s the next release of the game. Lots of new features. Can’t wait to see your next analysis. ;)

  12. Kyle says:

    Everybody says so, and everyone’s right.

    Rockets=Very Good
    Water=Awsome Support
    Fire=LET THEM BURN!!

  13. Kyle says:

    Oh yeah, and your calculations I find misleading. You’re looking at the upgrades. Overall, you get 1.3333333333…. damage per gold.

  14. Jason says:

    What i found works best for several levels is one cannon fully upgraded right in the middle. this hits a large amount of the path and is a grteat way to build interest while you wait until you need more

  15. The Meal says:

    Not sure if you’ll see responses to old entries, but there’s a super-fun version of this now available:


    The Easy mode is somewhat “Meh,” but when you upgrade to normal, then the run really starts. Give it a whirl, Seamus!


  16. JP says:

    I need a website not blocked by the edmonds school district. plz and thank you

  17. JP says:

    btw i have a stratigy that goes up to level 27 or something like that and am willing to share with anyone who can help. its a word document of screen shots. it gives about 150k if done right. i havent perfected the air levels or boss but up to 27 its almost perfect.

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