Week 5 Assignment: Midterm Progress Report

Organ Defenders (WIP)


For this project, I was inspired mostly by Namco’s Galaga (image attached) and other games in the shoot ’em up genre. In the game, there are waves of enemies that you have to shoot down to score points. Being shot by the enemy or colliding into them makes you lose a life. Finally, there are some enemies that have special attacks that don’t kill you outright but make it harder for you to survive the wave.

A game of Galaga. The player controls a spaceship that is trying to dodge attacks from enemy spaceships. The boss spaceship has a tractor beam that spreads out in front of itself towards the player.


As the Biology major of this class, I thought of combining the gameplay of Galaga with a concept based on our body’s immune system in order to make something new. Thus, Organ Defenders (would appreciate suggestions on the name) was born.


This can be divided into three aspects, the game design, the code structure, and the visual design.

Game Design: I mostly went with the tried and true format of Galaga. The player has four lives and can control a white blood cell in the x-axis at the bottom of the screen. The player will be able to shoot bullets of enzymes at the enemies to bring them down and score points.

Waves of bacteria and viruses keep generating at the top and moving downwards (I might change this to right-to-left later). I may give some of the bacteria the ability to shoot toxins later, but for now, colliding with a bacterium makes the player lose a life. Viruses won’t directly kill the player but will disable the gun control, thereby not being able to earn any points.

As mentioned before, score is earned based off of how many bacteria/viruses have been killed. If I have the time, I might create a hard mode, where the higher the number of bacteria/viruses that are allowed to leave the bottom of the screen, the higher the number of new bacteria that are generated at the top. This will attempt to simulate infection.

Additionally, I plan to include three different kinds of timed powerups that can also help the player in challenging situations. Again, the hard mode might include some kind of cost to use the powerups more than once, to prevent spamming. The powerups I am currently planning for will be Antibody Rush (freezes the bacteria/viruses in place), Cytokine Boost (the player will be able to shoot more projectiles per shot), and Complement Bomb (basically nukes everything on the screen).

Code Structure: I plan to have 4 classes: the white blood cell, bacteria, virus, and the bullet. Here’s an example of how the classes will look, using my Bacteria class.

class Bacteria {
  ) {
    this.x = initX;
    this.y = initY;
    this.r = radius
    this.moveY = speed;
    ellipse(this.x, this.y, 2 * this.r);
    this.y += this.moveY
    return dist(this.x, this.y, other.x, other.y) <= this.r + other.r
    return (this.y > height)

Visual Design: While it is a bit early to finalize the visual design before most of the gameplay is ready, I can still talk about it briefly. I plan to use Creative Commons-licensed sprites for the white blood cell, bacteria, and viruses. I might use spritesheets to show some animation, but I am not sure whether that will add to the game’s visual aspect as things might be going too fast anyway for a player to enjoy animations. At the most, I might include animations for when the white blood cell shoots a projectile.

Frightening Aspects / Challenges

There are quite a few aspects that seem daunting now:

  • Actually creating a desirable core gameplay loop, something that will encourage the player to keep playing
  • The powerups seem like a hassle to implement, especially the way I’m planning to implement them. Also, it will be challenging to show the timer of how much time is left before the next use of the projectile.
  • Timing of the animations will also need to be fine-tuned to avoid distracting the player and detracting from the game experience.
  • I also need to find a way to have the bacteria not clump together, which would unfairly make the player lose more lives. I tried for a bit to use while loops to keep regenerating random positions until there was a non-colliding one, but it didn’t seem to work properly.

Risk Prevention

  • I’ll have to work on extensive playtesting to resolve bugs. I also aim to have my roommates/friends playtest it to fine-tune the UI/UX.
  • Implementing the powerups will require me to learn some new skills.
  • I should have a core gameplay loop ready, along with visuals and SFX before I attempt to include the powerups, so that in the worst-case scenario, I still have a ready project.
  • Regarding the bacteria clumping together, I need to either find a way to unclump them or give the player i-frames (invincibility frames) upon losing a life. I might include the i-frames anyway, but will need to find a way to indicate that to the player (in fact, my prototype currently has half a second of i-frames, clearly not enough).
  • I should also make my code more responsive and check for any in-built functions I use that may respond unexpectedly on other systems.

Midterm Prototype

Finally, here’s the prototype. So far, only the player movements, the bacteria collisions, and the game over/game restart logic have been put in place.

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