Battle Garegga/Advanced Rank

Overview

Rank in Battle Garegga is a bounded integer. Its maximum value is 15,728,640, and its minimum value is 2,097,152 for "normal" DIP switch settings and "Arcade" mode in the Battle Garegga Rev.2016 port.

In the arcade release, rank is hidden from the player. However, the Battle Garegga Rev.2016 port allows the player to track rank as a percentage in real time in the "rank graph" M2 gadget. The rank% displayed in the rank graph is a simple linear conversion from the rank variable stored by the game:

rank% = 100 * [(max-rank)/(max-min)],

max = 15,728,640,

min = 2,097,152.

Note that the rank% is 0.0% when rank=max and 100.0% when rank=min. Thus, high rank means low difficulty and vice versa.

For a rank change from any given source, the conversion goes:

Δrank% = 100 * [Δrank / (max - min)]

Rank is updated every frame according to a value called the frame rank as well as other specific events. These events are firing the ship's main shot, firing an option, picking up an item, deploying the ship's special weapon, sealing an enemy bullet, and dying.

Note: The rank graph only displays rank% with one significant figure, which is larger than many rank changes throughout the game. Thus, tables of rank% will display more significant figures than encountered in game for the sake of accuracy.

Frame Rank

The frame rank consists of a base value, a multiplier, and extra additions. It is applied to the rank on every frame during a playthrough.

The base value depends on the game version and DIP switch difficulty, and is equal to 22 for the "normal" DIP switch on the Japanese arcade release and the "Arcade" mode of the Battle Garegga Rev.2016 port.

The multiplier depends on the maximum autofire rate activated by the player during the current credit, and is applied directly to the base frame rank.

The extra additions are increments of +1 or +2 that are added upon obtaining certain power ups. Levelling up the main shot with a small shot power up adds +1. Activating a secret option formation (except for wide formation) adds +2. These additions are not affected by the multiplier.

When changing the autofire rate, the new frame rank will be the current frame rank or the product of the base frame rank and the new multiplier, whichever is greater.

Because the frame rank is a small number, the total rank% change per second is included as well in the following table.

Autofire Rate	Multiplier	Frame Rank	Rank%	Rank% per second
8.6 Hz	x1	22	0.00016	0.00968
10 Hz	x1	22	0.00016	0.00968
12 Hz	x1.5	33	0.00024	0.01453
15 Hz	x2	44	0.00032	0.01937
20 Hz	x3	66	0.00048	0.02905
30 Hz	x4	88	0.00065	0.03873

Frame Rank Increment	Rank%	Rank% per second
+1	0.000007	0.00044
+2	0.000015	0.00088

Main Shot

The value of the rank increment applied whenever firing the main shot depends on the number of bullet "clusters" in the shot level of the ship being used and whether the cluster is of non-penetrating or penetrating bullets. The increment at any individual shot level is unique for each ship. In addition, if the sprite limit for player shots on screen has been reached due to a high autofire rate, the rank increment for shots not fired will still be applied.

Because the rank increment per shot is a small number for each ship and shot level, the rank% increase per second for each autofire rate is included in the tables below.

Option Shot

A rank increment is applied for every individual option bullet fired. The value of this increment is the same for all ships except for Gain and Miyamoto, whose option bullets have larger rank increments.

Items

The value added to the rank when collecting an item depends on the item, with two exceptions. The first exception is when collecting a shot power up, option, or bomb fragment at max capacity, which will increase the value added to rank. The second exception is when collecting a small shot power up or small bomb fragment that levels up the main shot or fills a bomb stock, which will also increase the rank added.

The total rank increase from collecting 40 small bomb fragments is also included in the table below for an easy comparison to collecting a single large bomb fragment.

Special Weapons

A rank increment is applied to the rank whenever activating the ship's special weapon. This value is applied regardless of whether a full bomb stock was used.

Sealing Bullets

A rank increment is applied for each individual bullet sealed. For the total rank increase, multiply this value by the number of bullets sealed for enemies that fire many bullets at once.

Dying

The rank increment upon death depends on the number of extra lives the player has on hand.

DIP Switches

Changing the DIP switch in the arcade version or in "Custom" mode of the Battle Garegga Rev.2016 port changes two things, the minimum rank and the base frame rank.

Because of the different minimum rank, the maximum in-game difficulty will change between settings even though the starting difficulty will remain the same. Even though the minimum rank changes, the rank% will still be calculated using the minimum rank of the "normal" DIP switch setting. As a result, the maximum possible rank% will change to a number greater or lower than 100.0% depending on the DIP switch setting.

Because of the different base frame ranks, the frame ranks encountered at different autofire rates will change accordingly.

References & Contributors

1. ST: Battle Garegga, https://shmups.system11.org/viewtopic.php?f=5&t=351