I’ve played these things to death over the years. As a kid I was obsessed with Galaga, Galaxians and the daddy Space Invaders. Each game improved on the one before. Where Invaders had the satisfying press the button, launch the missile accompanied by a sound Galaxians had it times two. Galaga went one better and actually presented you with a challenge in the way that the aliens swooped around the screen. Gunning them all down in quick succession was intensly rewarding.
With the rise of MAME I’ve taken to playing these and countless other shooters over recent years. My personal fondness for the so called manic shooter has seen me devouring Esp Ra De amongst others. In essence they are all Galaga with more action. The wonderful 1942 was the first shooter I remember that filled the screen with chaos in the later stages. In my own (as yet untitled) game I am aiming for the same thing. I suspect the final result will be somewhere between 1942 and a manic shooter. Frame rate permitting !
So what was it that made these games of old some damned enjoyable?
I think I have boiled it down to the fact that every action and reaction was tuned to be the ultimate in satisfaction. Simply pumping the lasers and watching your enemy break up was hugely satisfying. The fact that your ship became surrounded by adversaries and you had no choice but to blast your way out was intense and very rewarding. In keeping with the manic shooter style of defining a collision zone of just a single pixel in the centre of your ship I have tightened the bounding box on my own ship to be just a few pixels. This allows for more chaos !
Something else I noticed whilst messing with the numbers that drive the game was that shooting something and having it blow up was rewarding enough but actually having it recoil lifted the rewards to another level. I remembered pumping lead in to the Imps in Doom and wanted to recreate the same sense of power. Previously I had stopped the sprite from moving whilst it flipped through its death animation but this time around I set its direction to 0 (North) and watched with joy as it flipped through its death cycle whilst recoiling.
Messing with numbers like this gives you so many options.
Later levels will see aliens increase in size the more you shoot them a la Bangai O.
I doubt there is any single genre of video game that creates such a huge sense of enjoyment for me. Creating this stuff is the ultimate in fun. You can see current progress here.