The Hidden Blade Assassin's Creed in Depth

https://www.youtube.com/watch?v=eL5I94K35tY

Vector TDx is a tower defense game that you can play for free at candystand.com. There are 50 levels but the best players in the world can only make it to level 37. In this video I finally break the level 37 barrier and go all the way! (all the way to level 38, that is)

Introduction

If you've never played a tower defense game before it's pretty simple. The goal is to stop all the vectoids (usually called "creeps" in other games) from crossing the map by building towers that shoot them or slow them down. Every time you kill an vectoid you earn money which you can use to buy or upgrade towers. Whenever an enemy goes off the bottom of the map it wraps around to the top and you lose a life. The game is over when you lose all 20 of your lives.

Working the economic system is vital to success. Ideally you want to defeat all the vectoids while spending as little money as possible. At the beginning of each level your bank account earns interest. With careful budgeting, you can save over $12,000 for late in the game when you need it most.

Close, Hard, or Weak

Each tower has a targeting mode that can be set to "close", "hard", or "weak". A tower will automatically fire on any vectoid that is in range. When two or more vectoids are in range, the targeting mode controls which one is selected:

• CLOSE means to select the vectoid nearest the tower (minimum Euclidean distance).
• WEAK means to target the vectoid with the lowest remaining health
• HARD is the opposite and selects the vectoid with the most hitpoints

In case of a tie, WEAK and HARD seem to pick the leader of the pack.

In addition, towers that fire periodically have a "target locking" option:

• ON means to continue firing on the selected target until it's destroyed or goes out of range
• OFF means to select a new target for each shot as prescribed by the targeting mode above

Manual or Automatic

When you're ready to start the next level, there's a button that says "Release Vectoids". Most players use this button to manually advance the game and I definitely recommend it for beginners. There's also a checkbox called "Auto" that will automatically release the next wave of vectoids as soon as the previous wave is eliminated. This is what I used above, mostly to keep the video as short as possible.

The most important thing to understand is that you earn interest on what's in the bank at the time you release the vectoids. Whenever you sell a tower, this should be done before Release Vectoids so you'll earn interest on the proceeds of the sale. If you're just changing a tower's targeting options, this can be done before or after releasing the vectoids because it doesn't cost any money. However, you should only build/upgrade towers (i.e. spend money) after the vectoids have been released. This sometimes means you must work quickly. If you're going to build a Purple tower you may select it from the menu at the right, click "Release Vectoids", and immediately place it on the map. The game remembers that your cursor is carrying the Purple tower and won't drop it. This saves a click when time is tight.

Auto saves yet another click. You can have the Purple tower selected and hovering over the square where it is to be placed. As soon as the previous level is completed, just click once to place it (and click again if you need to upgrade it or change targeting). This is the biggest benefit of using Auto. The downside is that you have be on your toes and know which level you're on and what towers to place, if any. Some players think that you only earn interest when you manually press "Release Vectoids". This is not true. You earn the same interest with Auto.

Complete strategy to level 38

Without further ado, here's a step-by-step guide to my strategy. I number the grid like a chess board with columns A through V and rows 1 at the bottom through 18 at the top. So the bottom-left corner is A1 and the upper-right is V18. This is long. More detailed data follows the table.

Level	Step by step procedure	Max Score	Bank
1	Place a Green Laser 1 at K10, upgrade to level 2 and set target mode to WEAK Release Vectoids (Sometimes leaks 1)	8400	$209
2	No changes	19612	$327
3	Release Vectoids Upgrade Green tower to level 6	33631	$276
4	Set target mode to CLOSE Release Vectoids When first vectoid from second wave escapes around corner, switch target mode to WEAK	50447	$452
5	Leave target mode on WEAK Release Vectoids	70074	$661
6	No changes	92513	$904
7	Release Vectoids Upgrade Green tower to level 9	117767	$1033
8	No changes	145828	$1343
9	Release Vectoids Place a Blue Rays 1 at M11	176708	$1391
10	Release Vectoids Use bonus point to increase interest	210391	$1768
11	No changes	247003	$2238
12	No changes	286471	$2764
13	No changes	328802	$3349
14	Set Green tower target mode to CLOSE Release Vectoids Place a Purple Power 2 at L10 When Green tower is working on last vectoid from first wave, switch target mode to WEAK (Often leaks 1)	374003	$3097
15	Set Green tower target mode to CLOSE Release Vectoids	421974	$3758
16	Release Vectoids Place a Blue Rays 1 at K14 Upgrade Green tower to level 10 Place a Blue Rays 1 at N7 (Sometimes leaks 1 or 2)	472824	$3837
17	No changes	526484	$4599
18	Release Vectoids Wait until first wave comes into range Place a Blue Rays 1 at O14	583035	$5134
19	Release Vectoids Place a Blue Rays 1 at J10	642451	$5730
20	Set Purple power target lock to OFF Release Vectoids Place a Blue Rays 1 at L6 Use bonus point to place a Damage Booster at M7	704738	$6389
21	No changes	769904	$7416
22	No changes	837993	$8532
23	Release Vectoids Place two Blue Rays 1 at I14 and O9 As Purple tower is firing its eighth shot, switch target mode to WEAK When first wave is eliminated, switch target mode back to HARD	909016	$9143
24	Release Vectoids Upgrade Purple tower to level 3 Place two Blue Rays 1 at J6 and G12 When second wave enters range of Purple tower, switch target mode to WEAK When first wave is eliminated, switch target mode to HARD	982913	$8919
25	Set Purple tower target locking to ON Release Vectoids	1059583	$10210
26	Release Vectoids When second wave enters range of Purple tower, switch target mode to WEAK When first wave is eliminated, switch target mode to HARD (Sometimes leaks 1)	1139208	$11606
27	Sell Green tower Set Purple tower target mode to CLOSE Release Vectoids Upgrade Purple tower to level 7	1221850	$11751
28	Release Vectoids Upgrade Purple tower to level 9	1307260	$12396
29	Work very quickly! Release Vectoids Place two Purple Power 2 at K7 and J7 and upgrade both to level 6 Place a Blue Rays 1 at G7 (Usually leaks 1, sometimes as much as 3)	1395547	$7407
30	Set all Purple towers to target mode to CLOSE Release Vectoids Upgrade Purple towers on K7 and J7 to level 8 Use bonus point to place Damage Booster at K10	1486035	$6947
31	Release Vectoids Upgrade Purple towers on K7 and J7 to level 9	1579268	$7387
32	No changes	1675354	$8782
33	Work quickly Release Vectoids Place a Purple Power 2 at M10, upgrade to level 10, and set target mode to CLOSE Upgrade Purple towers on L10, K7 and J7 to level 10	1774407	$3988
34	Release Vectoids Place a Purple Power 2 at L7, upgrade to level 5, and set target mode to CLOSE Place three Blue Rays 1 at D7, D4 and I4	1875685	$1635
35	No changes	1979481	$1834
36	Release Vectoids Upgrade Purple tower on L7 to level 8	2086213	$2649
37	Set all Purple towers target mode to WEAK and target lock OFF Release Vectoids Place three Blue Rays 1 at D17, F15 and M17 Upgrade Purple tower on L7 to level 10 Place three Blue Rays 1 at P11, M4 and K4 When money is available, place two Blue Rays 1 at Q4 and G4 (Usually leaks 15 to 17)	~2129430	$299
38	Work in progress: Set Purple tower on M10 target mode to CLOSE and target lock ON Release Vectoids Place two Blue Rays 1 at O10 and G10 Just before first vectoid leaves screen, press QUIT	~2197591	N/A

Selecting the best towers

The most important factor in deciding what type of tower to build is value: damage per second per dollar. The game tells you the price and damage capabilities of each tower. For example, a Green Laser 1 costs $100 and causes 22 damage whereas a Purple Power 2 costs $900 and has 8500 damage. Taken at face value these statistics are useless. What they don't tell you is that the Green Laser fires 40 times per second, so its damage per second is 880. The Purple Power 2 fires once per second but it has two beams, so its actual damage is 17000 per second! Here's a useful comparison table:

Tower	Cost	Damage per shot	Shots per second	Damage per second	Value (damage per second per dollar)
Green Laser 1	$100	22	40	880	8.8
1Green Laser 2	$400	45 - 90	40	1800 - 3600	4.5 - 9.0
1Green Laser 3	$2000	200 - 600	40	8000 - 24000	4 - 12
1Red Refractor	$200	110 - 440	4	440 - 1760	2.2 - 8.8
Little Red Spammer	$800	600	4	2400	3
2Red Rockets	$2500	30000	up to 1	30000	up to 12
Purple Power 1	$300	2650	1	2650	8.83
Purple Power 2	$900	8500	1	17000	18.89
Purple Power 3	$2800	22000	1	22000	7.86

¹ Red Refractor and Green Lasers 2 and 3 can damage multiple targets in proximity to one another.
² Red Rockets may fire less than once per second. When it already has two rockets in the air, it won't fire a third until one of them hits a target.

So the Purple Power 2 is the best value on the board. At the beginning of the game when you only have $275 to spend, Green Laser 1 is a better choice than Red Refractor.

Hitpoints

The main reason Vector TDx is unbeatable is that vectoid hitpoints increase geometrically while money (and thus tower strength) only grows linearly. Here are the hitpoints, score and dollar value for every level. Note that when you kill a vectoid the points are added to your score but when you lose a life, the points are subtracted from your score. So it's better to lose a life early in the game than late. The same is not true of the dollar amount. Your bank account does not go down when you lose a life.

Level	Vectoid Type	Hitpoints	Score	Bounty
1	Blue Spinner	850	300	$3
2	Green Flyer	926	400	$4
3	Red Shredder	1016	500	$5
4	Yellow Sprinter	1123	600	$6
5	Big Purple Box	1251	700	$7
6	Green Flyer	1403	800	$8
7	Red Shredder	1585	900	$9
8	Orange Regener	1803	1000	$10
9	Yellow Sprinter	2066	1100	$11
10	Hard Grey	2384	1200	$12
11	Red Shredder	2770	1300	$13
12	Green Flyer	3240	1400	$14
13	Blue Spinner	3816	1500	$15
14	Yellow Sprinter	4525	1600	$16
15	Big Purple Box	5402	1700	$17
16	Orange Spurter	6493	1800	$18
17	Red Shredder	7856	1900	$19
18	Orange Regener	9568	2000	$20
19	Yellow Sprinter	11730	2100	$21
20	Hard Grey	14474	2200	$22
21	Blue Spinner	17976	2300	$23
22	Green Flyer	22470	2400	$24
23	Red Shredder	28267	2500	$25
24	Yellow Sprinter	35786	2600	$26
25	Big Purple Box	45591	2700	$27
26	Green Flyer	58447	2800	$28
27	Orange Regener	75396	2900	$29
28	Red Shredder	97864	3000	$30
29	Orange Spurter	127810	3100	$31
30	Hard Grey	167942	3200	$32
31	Red Shredder	222019	3300	$33
32	Green Flyer	295285	3400	$34
33	Orange Regener	395091	3500	$35
34	Yellow Sprinter	531792	3600	$36
35	Big Purple Box	720046	3700	$37
36	Green Flyer	980702	3800	$38
37	Orange Regener	1343561	3900	$39
38	Red Shredder	1851427	4000	$40
39	Orange Spurter	2566077	4100	$41
40	Hard Grey	3577111	4200	$42
41	Blue Spinner	5015109	4300	$43
42	Green Flyer	7010303	4400	$44
43	Orange Spurter	10027107	4500	$45
44	Yellow Sprinter	14298654	4600	$46
45	Orange Regener	20504269	4700	$47
46	Blue Spinner	29567155	4800	$48
47	Orange Regener	42872374	4900	$49
48	Orange Spurter	62507921	5000	$50
49	Orange Regener	91636612	5100	$51
50	Orange Spurter	200177246	5200	$52

Acknowledgments

This is an old game, published in October 2007. Most of the discussion about it occurred on websites that are no longer in existence. I was able to reconstruct what happened through the Internet Archive Wayback Machine. The pioneer in reaching level 37 was torz77. He documented his strategy and provided a companion video, THB style. Dcramer came up with putting Blue Rays in the bottom left corner, which I expanded upon map-wide for level 37. Someone named Karabin claims he made it to level 39 with a score of 2,260,685. He never revealed his strategy and others were skeptical. I don't know if he's on the level but he did have some good tips like "don't put your blue towers right next to each other" which worked well for me.

Finally, Blader wrote a trainer (i.e. cheat engine) for Vector TDx. I was able to download it with the Wayback Machine and it still works. However, it's of limited use because most of the features weren't implemented correctly. There's no way to skip directly to level 37 or replay it over and over. All you can do is give yourself unlimited lives, money and bonus points. With that you can speed up the game (by buying powerful towers and selling them later) but you still have to sit through levels 1 - 36.