A beginning

This post is mainly made as a form of guidance for myself after tackling several shmup games (Ranging from simple jam entries in the spirit of simple shmups akin to Space Invaders and 1942 and more advanced shmups) in attempt to understand how a basic enemy unit can be designed, and what cliches can be found in common between said games.

Let’s get into it

An enemy can be divided into 3 phases:

  1. Intro
  2. Action
  3. Departure

Intro attributes

Name Description
None The enemy simply moves into the scene, getting instantly into the action phase.
None animation A forward moving enemy, no intro animation
Tween to position The enemy tweens into a specific position, usually accompanied by being instantiated in other spots of the screen and different types of tweening to provide interesting effects.
Tween animation An enemy tweening to position, linear interpolation and easing in-out
Foreground animation The enemy has an animation, usually scaling down if coming from the foreground, disabling its hitbox through the animation.
Foreground animation An enemy coming from the foreground, done with 2 tweens
Teleport The enemy has a teleportation animation before being instantiated/spawned in place of the animation.

Action attributes

The action attributes are split into two types:

  1. Movement attributes
  2. Shooting attributes

The types can be either simultaneous, or focused on one of the types.

Movement attributes

Name Description
Straight line The enemy moves in a straight line. Can be either of a moderate speed, the background’s scrolling speed (if the enemy is part of the ground/stationary) or slow to imply heaviness. (for bullet sponges and bomb-types)
Straight line animation An enemy moving in a straight line
At player The enemy moves in the player’s direction, similar speed traits as the straight line variant.
Sinewave The enemy moves in a sine wave vertically while having normal horizontal movement. Multiples can be used to create interesting shapes. (Wave, reverse sine)
Sinewave animation Enemies moving in a sine wave, one then multiple
Zigzag The enemy moves forward then up and back before continuing forward to resemble a zigzag shape.
Zigzag animation An enemy moving in a downwards zigzag
Dash The enemy moves in a bigger speed than a regular enemy, usually combined with an intro.
Repositioning The enemy moves around a set of predefined spots. Can be combined with shooting projectiles after moving through such spots or during every movement.
Repositioning animation An enemy repositioning across various spots, shooting after stopping at selected times
Hovering The enemy moves around the scene slowly, usually used for bigger enemies or bosses to stop them from being completely stationary.
Hovering animation The closest approximation to such a behavior with a small enemy

Shooting attributes

Name Description
Straight line The enemy shoots a projectile (or a cluster) that moves forward.
Straight shot animation An enemy shooting forward
At player The enemy shoots a projectile (or a cluster) that moves in the player’s direction.
At player animation An enemy shooting a cluster in the player’s direction
Spread shot The enemy shoots more than one projectile at once, spread to shape an arc. The arc’s main angle can be either a forward line, or in a specific direction. (ie. the player’s)
Spread shot animation An enemy shooting 3 projectiles
Spraying The enemy scatters multiple projectiles (or clusters) with a brief gap between each projectile, akin to using a machine gun to spray bullets.
Spray shot animation An enemy spraying 5 projectiles
Radial blast The enemy shoots projectiles spread in the shape of a circle at once. Changing angles between blasts can provide an interesting challenge (used in danmakus/bullet hell games)
Radial blast animation An enemy shooting 10 projectiles in a circle
Charging (Special) The enemy takes a moment to charge before blasting multiple shots, one after another. The projectile style can be any of the attributes discussed above.
Bomb
(Special)		 The enemy triggers the shots like a bomb when killed, usually using a radial blast.

Departure attributes

Name Description
None The enemy continues with the action phase, usually found in movement-focused enemies.
Movement The enemy uses one of the movement attributes as a way to leave the scene, usually used after a shooting attribute/phase that takes a longer time.
Disappearing The enemy has another teleportation animation to leave the scene, which can be used as a way to reward the player for quickly defeating the enemy before disappearing.

References

I was heavily inspired by Garret Bright’s Build a Bad Guy Workshop article and how he structured the article, definitely worth a read. I played:

  • Twin Strike (pico8 game) by Mikesta
  • Warwind (pico8 game, jam entry) by LouieChapm
  • ZeroRanger (Demo) by System Erasure
  • Lords of Thunder (Sega CD) by Red Entertainment/Hudson Soft
  • Gunbird 1 and 2 (Arcade, Sega Dreamcast) by Psikyo

I watched the playthroughs of: