Boss Battle Analysis

   I'll be analyzing the boss battle from the first level in the game Jamestown. Jamestown is a vertically scrolling shoot'em up game where you fly through levels in a ship of your choice and shoot at enemies while dodging the bullets that they shoot at you. Every ship in the game has a primary and secondary weapon, each with its own advantages and drawbacks. For instance, the ship that you start with has a scatter shot that covers a wide area, but does less damage, or a laser beam that does a lot of damage over a small area. As the player shoots enemies, they drop coins that can be collected to increase his or her score. After surviving for a long enough time and accumulating enough points, you get a shield power up that you can activate at any point for a limited time. The difficulty of the game ramps up very quickly and even this first boss is pretty challenging to beat.
  The initial encounter with the boss is established as the screen begins to slow down and a burning cabin comes into view. As soon as you reach this point, you are confronted with the boss and the battle immediately begins. There is a very specific pattern to the boss battle that depends on how much health the boss has left. It starts out with the boss shooting a few scattered bullets that are easy to dodge. Then the boss shoots some homing bullets that take a bit more maneuvering to avoid.

Its fairly simple to dodge these red homing bullets

Next, the boss will shoot the scattered or homing bullets as a huge wave of enemies travels down either the right or left side of the screen.

The wave of enemies increases the challenge while adding some variety to the fight.

The wave of enemies adds more difficulty to the previous obstacles, while also adding a rewarding element because its a lot of fun to shoot at these easier enemies and they drop a lot of gold to collect. The boss will continue cycling through these three actions until his health is lowered to the halfway point.
After passing the halfway point, the arrangement of the bullets starts to become much more complex. First, there is a stream of bullets that radiate outwards from the boss, which requires faster reflexes to avoid. This section consists mostly of the standard blue bullets mixed with some of the red homing bullets.

Next, the boss creates a sort of spiral pattern of bullets which are very difficult to dodge, requiring a lot of quick back and forth movement. Due to the spiral pattern, there also tends to be far more bullets towards the center of the boss, meaning that its far more risky to stay in the center to shoot at the boss, as opposed to staying towards the edge where your bullets will be out of range.

 Finally, the boss shoots out a substantial amount of red homing bullets that travel very quickly towards the player. This tends to force the player to move away from the boss, meaning that they will have to regain a position that's in range after.

Again, the boss continues to repeat these moves until he is defeated. During this section, the player is occasionally rewarded with some gold coins after doing damage to the boss. After defeating the boss, the final reward is some victory music along with a screen that comes up, counting out bonus points and rewarding the player with stars and achievements depending on how well they did in the level.

Here's a sketch of the major parts to the boss battle:

Here's a link to a video with this boss battle in it, it begins two minutes in.