Vacant Ark

Vacant Ark(ヴェイカント・アーク in Japanese) is a horizontal doujin shooter developed by Buster in 2005 for Windows 95/98/ME/XP using Shooting Tkool 95. The game takes inspiration from past shooters such as Radiant Silvergun, Darius and R-Type series with its atmospheric deep sea settings and option/weapon system. The game spans over 3 hadal zones(A, B, and C) each one with numbered subzones. In addition, there are 4 difficulties. Practice, Easy, Normal, and Hard(dubbed Shallow, Middle, Deep, and Abyss respectively). The gameplay is somewhat novel. Boasting an interesting ammo economy, demanding awareness and precise execution from the player. Gameplay details will be further explained below.

For replay videos, visit the Video Index.

Controls

Just like many Windows games. Vacant Ark utilizes the keyboard for controls.

• Arrow Keys: navigates the menu and moves the character.
• Shift/Enter/Space: Confirm button in the menu.
• Z: Shoots weapon currently equipped. No autofire.
• X: Cycles to the next weapon(Cannon > Riot > Force).

Other controls

• Q: Quits back to the title screen or resets score and skips to the next zone(not much is understood about this function, but killing an enemy and collecting a fish stone seems to consistently do the latter).
• F1: Pauses the game. Game can be paused at any time.

Gameplay

The player controls a Cyborg mermaid with 3 cycleable weapons and a 6 ammunitions. Each weapon use consumes 1 ammo. When the player doesn't shoot. An option spawns on a position depending on what weapon is currently equipped. If the player is out of ammo. Then the player shoots a close range low-damaging shot instead. The player always starts with 3 lives and full ammo. Lives can be increased up to 6. There are 4 different difficulties each with their differences. And the run consists of 3 Zones with 4 subzones each.

Player hitbox

The player hitbox is placed on the chest of the mermaid indicated by the white orb. Exact size is unconfirmed.

Auto-Shield

Getting hit by a bullet or an obstacle protects the player from losing a life but empties the ammunition. Getting hit with empty ammunition will take away one life.

Weapons

It's important to note that every weapon fires in front of the player sprite and that the option position has nothing to do with where it fires. Rather, the options act as a shield that erases bullets and deals tick damage to enemies.

Icon	Weapon	Option	Description
	Cannon	Front	Shoots a fast single-targeting projectile. Deals a considerable amount of damage and has a fast fire-rate. The projectile can sometimes erase bullets on the way. Useful for bosses and high HP enemies.
	Riot	Orbit/Rolling	Shoots a burst of bubbles. Deals relatively low damage but can be aimed by moving vertically. Slow fire-rate and has semi-piercing property. Useful for dealing with zakos and other low HP enemies. Useless on Abyss difficulty(refer to the Difficulties section).
	Force	Back	Enchants a close range Force-field that erases bullets and turns them into small explosions. Those small explosions can turn other bullets into more explosions thus causing a chain reaction. In a vacuum the weapon deals moderate damage with a moderate fire-rate. By far the most versatile weapon in the game and in the right situations deals more damage than the cannon albeit less consistent.

Items

Icon	Name	Description
	Fish Stone	Acts as a score item and replenishes ammo. They are obtained by defeating an enemy, erasing bullets or after defeating a boss. Auto-collection of all fish stones on screen is done by cycling weapons.
	Life/2X Ratio	After killing enough enemies. A tune will play and an item will appear in the middle of the screen. It will start as a Life item which increases your HP(The red gems seen on the top right). If the player waits a couple of seconds, the Life item will drift slowly to the left then turn into a 2X ratio and will start floating upwards slightly. The 2X ratio as the name entails, doubles your counter value. How close the player is to getting this item is indicated by a thin red bar under the live count on the top right.

Secret Extend

The red mermaid during Zone C

Upon defeating the red mermaid during Zone C. The player will be rewarded with a Life/2X Ratio.

Difficulties

Difficulty select

Name	Description
Shallow	A trail mode of sorts, spawns a fish stone every couple of seconds. The run ends after the first zone. The Q key can still access different zones.
Middle	Easy mode, no revenge bullets. Overall slightly easier patterns and less aggressive enemies.
Deep	Normal mode, minimal revenge bullets.
Abyss	Hard mode, Lots of revenge bullets. Most enemies shoot back bullets instead of rewarding fish stones. Some enemies/bosses are more aggressive.

Because of revenge bullets in higher difficulties. The Riot weapon becomes a liability because it can put the player in danger. Thus, Force becomes essential especially on Abyss.

Scoring

Ammo and Fish Stone Counter.

Scoring in Vacant Ark is straight forward. It involves the Fish stones and Fish Stone Counter. Located under the ammo chamber on the top left. This counter increases when killing enemies/bosses and doubles in amount when collecting a 2X Ratio. What this counter entails is that the Fish Stone(base value at 10pts) is multiplied by the current counter value. The counter can counterstop at +25600 and depletes slowly but freezes when a boss is defeated. Other factors that can affect the counter is the option. While it does help in erasing bullets and produces tick points. Whenever the options come in contact with an obstacle, wall, enemy, or a bullet. The counter starts decreasing faster. It is highly encouraged to not use options for anything other than erasing a few bullets if the player wants to score. Since the counter depletes slowly. The player should find the most efficient ways to defeat bosses as fast as possible to maintain a high counter value. In some situations the player can milk fish stones by using the Force weapon to erase a large cluster of bullets. But the player has to also damage the boss while also milking at the same time to make sure the boss is defeated fast.

Triggering Auto-Sheild takes away a flat 3,000 from the counter. But losing a life takes away 50% of the counter.