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Submission #4026: £e Nécroyeur's NES Defender of the Crown in 01:46.31

Console: Nintendo Entertainment System
Game name: Defender of the Crown
Game version: USA
ROM filename: Defender of the Crown (U) [!].nes
Branch:
Emulator: FCEUX 2.2.1
Movie length: 01:46.31
FrameCount: 6389
Re-record count: 5572
Author's real name: George Murphy
Author's nickname: £e Nécroyeur
Submitter: £e Nécroyeur
Submitted at: 2013-07-26 07:33:30
Text last edited at: 2016-12-18 04:54:15
Text last edited by: £e Nécroyeur
Download: Download (944 bytes)
Status: published
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Author's comments and explanations:

(Link to video)


Defender of the Crown is a strategy game (loosely based on Ivanhoe) originally released by Cinemaware for the Commodore Amiga in 1986, and was later ported to many other home computer systems and game consoles. The NES port of the game is a far cry from the Amiga version, but in the context of a TAS, this version is likely much faster.


Game Objectives

  • Emulator used: FCEUX 2.2.1
  • Aims for fastest time
  • Manipulates luck
  • Crushes a Norman usurper


Tricks and Glitches

There are several methods used in this TAS to manipulate event outcomes:

Delaying for 1 or more Frames

The number of Frames that the A button was held when the previous command was entered

The Frame on which the last input was entered for the previous command

Many commands in the game require a brief screen transition. If the A button is pressed to enter such a command on an odd-numbered Frame, the screen transition will be 1 Frame longer than the same command entered on an even-numbered Frame. For example, if A button is pressed on Frame 100, the screen transition would be 9 Frames long, and if the A button is pressed on Frame 101, the screen transition would be 10 Frames long. Unfortunately, this policy is often reversed, and an odd-numbered Frame yields a shorter transition, so this must be observed for each individual transition in the game. This policy can't really be used to save Frames as such, but it does provide options as to what Frame to place input, which allows some manipulation without sacrificing any Frames.

The outcome of any given command is determined to some degree by the Frame on which the previous command input was entered. For example, if "Done" is selected on the "Transfer Forces" screen on Frame 100 on Turn 1, and then the Player conquers an unclaimed Territory on Turn 2, the enemy may Raid a Player's castle after Turn 2 has ended. However, if "Done" is selected on the "Transfer Forces" screen on Frame 101 on Turn 1, and then the Player conquers an unclaimed Territory on Turn 2 just the same as in the previous example, the enemy may choose a different command, and the Raid can thus be avoided. Another method to manipulate event outcomes is to hold the A button for 5 Frames (or longer, as needed) when entering a command.

When using "Move Army" between the Player's own Territories, the A button can be held down for more than 1 Frame to prevent the cursor from resetting until the A button is released. Holding the A button for 2 Frames or more will manipulate the RNG as needed to manipulate event outcomes. If the A button is released, then held again for 2 Frames or more starting on the Lag Frame when the army's icon moves, the same effect is achieved. Note that this will not work when using "Move Army" onto an allied, unclaimed, or enemy Territory, because under such circumstances the game accepts only the first Frame of input, and immediately begins the transition to the next screen.

Between Turns during the game, there is a (very good) chance of a random event occurring (the "Meanwhile..." screen). One of the allied Knight's daughters may be kidnapped. Refusing to rescue her will cause the Player's Knight's Leadership Rating to decrease by 1 factor. Choosing to rescue her involves a lengthy sub-quest. Obviously, either of these are unacceptable in TAS terms, so kidnappings have been manipulated not to occur at all in this run. Another random event is raiding of the Player's Castle, causing the Player to lose half his Gold. A Castle raid occurs once in this TAS, but required only 8 additional Frames and could not be manipulated without causing worse problems (the loss of the Gold itself was a moot point, as no Gold is required after November).

When de-selecting the last unit type on the "Buy Army" or "Transfer" screens, the A button can be held down for more than 1 Frame to prevent the cursor from resetting until the A button is released. Holding the A button for 2 Frames or more starting on the Lag Frame will manipulate the RNG as needed to manipulate event outcomes.

After the A button has been pressed to begin "The Attack", the result of changing to a different Option changes on Frame 42 of "The Attack", and then changes again every 31 Frames thereafter. For example, if "The Attack" begins at Frame 100, and the Option is changed to Bombard on Frame 141, the result would be the same as if the Option had been changed on Frame 100-140. However, if the Option is changed to Bombard on Frame 142, the result would be different. Note that changing the Option refers to the Frame on which the A button is pressed to confirm the Option: it doesn't matter on what Frame the directional input is entered.

Comments

To complete the game, the Player must conquer the Territories of Cornwall, Buckingham, and Norfolk.

A Knight's Leadership Rating determines the effectiveness of his Army in battle (and the speed of the crossbow during the.. never mind that now). Leadership ranges, from lowest to highest, Weak, Average, Good, and Strong. In the game, it acts as an attack multiplier for the various units in an Army. A higher Leadership Rating means faster destruction of the enemy during "The Attack", which could otherwise be incredibly time-consuming.

Cedric of Rotherwood is the only playable Knight in the game with a Leadership Rating of Strong. This makes him the obvious choice for a TAS.

Robin Hood will destroy 8 enemy Soldiers (of a Garrison of 30) before a battle if you enlist his aid. If there are fewer than 30 Soldiers in the enemy Garrison (due to Disease or Greek Fire), Robin Hood will destroy slightly fewer soldiers, to a minimum of 5. These enemy Soldiers will be destroyed by Robin Hood's attack, "The Ambush", after "The Siege" but before "The Attack". You can get Robin's help a total of 3 times: just enough for this TAS.

Dorset must be conquered to have any access to attack Cornwall. The enemy Knight from Cornwall will conquer Dorset. Even if he is manipulated to not do so in October, and the Player conquers Dorset in November, The Cornwall Knight will attack at Dorset during his Turn, intercepting the Player's Army. For these reasons, Dorset must be conquered as quickly as possible, and by extension Cornwall also.

Gloucester has 12 Vassals and an Income of 7. That's 4 more Vassals than any other Territory in the game, and as much Income as any other Territory in the game. Moreover, it can be conquered on the first Turn, if the Player's Knight begins at Clwyd.

Buying 5 Soldiers requires 39 additional Frames compared to buying only a Catapult. Transferring 5 Soldiers requires 39 additional Frames compared to Transferring only a Catapult. Thus, 78 additional Frames are required to field 5 additional Soldiers. That's (78 / 3 = 26) Frames per battle, a negligible sacrifice compared to the cumulative effect of possessing even just a few more Soldiers, particularly considering that not a single Soldier is lost in the first 2 battles.

The outcome of "The Attack" is determined when the A button is pressed for the 2nd time on "The Attack" introduction screen. This can be easily manipulated.

By pressing the A button on the same Frame as the last directional input (e.g. navigating to and selecting an item in a menu), 1 Frame of input can be saved. Often, an additional Frame is saved as well simply because a transition was started on an earlier Frame.

To quickly open the main menu after using the Move Army command, simply hover the Cursor on or near the Knight icon (the mounted horse) and press the A button. The Cursor must be precisely positioned; the target area is only 4 pixels wide by 1 pixel high. Note that the exact location to position the Cursor relative to the Knight icon is slightly different for each Territory.

On the "Choose a Character" screen, it takes 11 Frames to change from one character to another (1 Frame of input and 10 Frames of transition Lag and delay). Changing to Cedric of Rotherwood requires 22 additional Frames.

Edmund the Grim captures Hampshire from the Player Knight after Cornwall has been conquered, which requires at least 180 Frames. In this TAS, it is unavoidable. However, in so doing, the additional 3 Income that Hampshire would have brought is avoided, saving 21 Frames on the Income tally screen.

Visiting Robin Hood from Clwyd requires 53 Frames.

Visiting Robin Hood from Cambridge requires 43 Frames.

For a CPU-controlled Knight to conquer an unclaimed Territory, 13 Frames are required.

For a CPU-controlled Knight to conquer an enemy Territory, 195 Frames are required.

"The Siege"

"The Siege" may last up to 6 Days (Turns), but may be cancelled earlier than that. This TAS uses only 4 Days for the first 2 battles, then 1 Day for the final battle.

Using Greek Fire will destroy 3 enemy Soldiers in the Garrison. If Greek Fire is used after Disease has been used, it will destroy fewer Soldiers. Greek Fire does not destroy enough enemy Soldiers to offset the number of Frames required to fire it, so it is not used in this TAS.

Using Disease on Day 1 of "The Siege" will destroy 10 enemy Soldiers in the Garrison. Using it on Day 1 allows the Disease more time to spread throughout the enemy Castle. If it is used on a later Day, it will destroy progressively fewer Soldiers, to a minimum of 1 if it is used on Day 6. If Disease is used after Greek Fire has been used, it will destroy fewer Soldiers. Disease could be fired slightly more quickly over a slightly damaged Castle wall on Day 2, but it would destroy only 9 Soldiers--not enough to offset the number of Frames required to destroy 1 additional Soldier during "The Attack".

Boulders are used to damage an enemy Castle's wall. The condition of an enemy's castle wall after "The Siege" determines the defense of the enemy Soldiers during "The Attack". The more damage that has been inflicted on the wall, the lower the enemy Soldier's defense. As such, Boulders are more effective than Greek Fire or even Disease at changing the outcome of "The Attack", despite the fact that Boulders cannot destroy Soldiers directly during "The Siege" as do Greek Fire and Disease. After 3 Boulders have damaged the Castle wall, their effectiveness drops sharply, and they no longer lower the enemy Army's defense sufficiently to offset the number of Frames required to fire subsequent Boulders.

Firing Greek Fire over an undamaged castle wall requires 249 Frames. For each level of damage to the castle wall, subtract 21 Frames from the total. For example, at 1 level of damage to the castle wall, the total Frames to fire Greek Fire would be 249 - 21 = 228 Frames. This adjusts for the shorter draw time on the Catapult and the consequently shorter flight time for the projectile.

Firing Disease over an undamaged Castle wall requires 245 Frames. For each level of damage to the Castle wall, subtract 21 Frames from the total. For example, at 1 level of damage to the Castle wall, the total Frames to fire Disease would be 245 - 21 = 224 Frames. This adjusts for the shorter draw time on the Catapult and the consequently shorter flight time for the projectile.

Firing Boulders at an undamaged Castle wall requires 210 Frames. For each level of damage to the Castle wall, subtract 21 Frames from the total. For example, at 1 level of damage to the Castle wall, the total Frames to fire Boulders would be 210 - 21 = 189 Frames. This adjusts for the shorter draw time on the Catapult and the consequently shorter flight time for the projectile.

Month By Month Comments

Game start

The desired result is as follows:

Cedric of Rotherwood is chosen (see Comments).

Begin the game with the Territory of Clwyd. This is necessary to defeat the enemy Knight from Cornwall (southwest coast) as quickly as possible.

Must not be attacked at Gloucester in November.

There must not be an enemy Army present at Dorset in December.

Must have direct access to attack Norfolk (east coast) in March.

CPU-controlled Knights conquer a minimum of enemy (claimed) Territories (see Comments). This occurs only 2 times in this TAS.

These are all critical points, and they are all determined prior to the first Turn of the game. Some manipulation of these events is possible after the game has started, but it only allows for 1 alternative outcome, so manipulation prior to game start is still critical. From the first push of the A button, the RNG is manipulated by entering input on odd or even Frames (see Tricks and Glitches) in a specific combination, so as to set up a successful game throughout. Specifically, the A button is pressed 1 Frame later than necessary on Frames 14, 52, 63, and 74, with no Frames lost by doing so.

October 1149

Transfer Forces from Garrison into Army.

Conquer Gloucester. Gloucester is the most resource-rich Territory in the game, plus it allows direct access to attack Dorset (due south of Gloucester).

November 1149

Buy Army. A Catapult is required to conquer a Territory that has a Castle. Now that there is sufficient (15) Gold in the treasury, one can be purchased. The remaining Gold is used to purchase additional Soldiers; this is well worth the 78 Frames required to buy and Transfer them.

December 1149

Move Army to Clwyd.

Transfer Forces to move the units purchased in November from the Garrison to the Army.

Move Army to Gloucester. The A button is held for several Frames longer than necessary to confirm this Move to prevent a kidnapping event after conquering Dorset.

Conquer Dorset. Because the enemy Army is away at Hampshire (as manipulated), Dorset is conquered without a battle, saving untold hundreds of Frames.

January 1150

Visit Robin Hood (see Comments).

Conquer Cornwall to defeat Reginald Front de Boeuf. For optimum efficiency, Disease is fired on Day 1 of "The Siege", followed by 3 Boulders (see Comments). The start of "The Attack" is delayed several Frames to manipulate the fastest possible victory. The Bombard Option has the greatest potential effect for destroying the enemy. Furthermore, the specific Frame on which the Option is changed alters the outcome; this has also been optimized. After leaving Bombard selected for a time, the Option is changed to Outflank to prevent a kidnapping event after conquering Cornwall. Mercifully, changing the Option to Outflank in this case is equally as effective as Bombard, and does not change on what Frame "The Attack" is completed.

February 1150

Move Army to Dorset.

Move Army to Gloucester.

Visit Robin Hood. It is faster to visit Robin Hood from here than from Cornwall or Dorset.

Conquer Buckingham to defeat Philip Malvoisin. This battle plays roughly the same as the first, but without the need to change Options twice.

The Treasury at Clwyd is Raided; Normans have stolen half of the Gold. Too little, too late! 8 Frames are required to cancel these screens, but this is far better than the alternative, in which a CPU-controlled Knight conquers an additional enemy Territory.

March 1150

Move Army to Cambridge.

Visit Robin Hood. It is faster to visit Robin Hood from here than from Buckingham.

Conquer Norfolk to defeat Edmund the Grim. This is the final battle, and is planned such that a minimum of input can be entered to ensure success.

"The Siege" is minimized here--no Disease, and just 1 Boulder.

Frame 6388 Press Down and A to change to Bombard.

Frame 6389 End input.

Other Comments

This is my second TAS. My first TAS was very challenging, so I chose a more simple project this time, and was able to complete it in less than a month. Now that I've taken a break, I will have to find something a bit longer to TAS next.

This TAS completes the game in just under half the time of the (not quite) optimized (not quite) published movie (the "B-Side" of [1268] NES Adventures of Lolo (USA) by Baxter & Zugzwang in 22:24.68).

I will expand this submission text at another time.


Mothrayas: Judging.

Mothrayas: Accepting for the Vault.


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