Old Flash Work

Jan 2010 - Fast Pace Shooter

The typical implementation of a 2D "shoot 'em up" (abbreviated as shmup) game encounters some classical problems as the speed of the game is increased. Increasing the speed of the game is one of the ways of increasing the intensity and potential the reward and satisfaction of the game. I explored a few techniques of how to increase the speed and intensity of a shmup.

Scrolling background layers quickly can get the sensation of flying through space quickly. Eventually you reach a scrolling speed where the elements of the background jump too much from frame to frame destroying the illusion of fast motion. Coupling a slow moving background layer with a faster moving foreground layer can give the impression moving quickly in space. Pre-blurring the fast moving layer in the direction of movement allows a higher speed to be used on the layer and still be perceived as fast movmement. This allows a perceived increase in speed without having to change any of the game's implementation.

Having many on the screen at the same time can increase the intensity without having to up the speed. The "bullethell" sub-genre fill the screen with often slow moving bullets. The individual bullets often move in linear or very simple trajectories. The difficulty comes is in how these many paths intersect. Instead of this, I used basic flocking behavior based on the boid model to increase the number of actual opponents on the screen each moving in an unpredictable but believable way.

Fast moving bullets can "teleport" through enemoies if collision detection is only done on the position of objects from frame to frame. Instead, I used the the swept AABB of the bullets/enemies based on the previous frame and current to check to see if a bullet collided at any point inbetween the frame.