Shooter Gallery #2: First Steps from Space Invaders

In the year following the release of Space Invaders (1978), game companies scrambled to improve upon the design.  Better resource management would gradually allow developers to cram more bang for the buck into arcade cabinets, but not all "improvements" turned out well.  Here are some things that developers experimented with in that first year.

Experiment: Geometry

Cosmic Guerilla

Animation demonstrating gameplay from the 1979 arcade game, Cosmic Guerilla.  Includes animated sprites of the aliens, player, and UFO.

Universal, who would later become known for pioneering platformers, turned the Space Invaders playing field on its head.  Instead of sending the aliens down towards the player, they brought them in from the side.  The player is at the bottom, as usual, and still has to avoid being shot, but the aliens' primary targets are his reserves ("lives") at the center of the playing field, which are protected by rows of what look like little soldiers.

During gameplay, the aliens waddle back-and-forth, picking up soldiers and carrying them back to the edge of the screen.  If that's not odd enough, a comb-like monster -- who you may recognize from Universal's Space Invaders clone, Cosmic Monsters -- occasionally zips in near the bottom of the playing field to take potshots at the player.

The game also includes a "rescue" element, where you can knock the aliens off as they try to carry away soldiers.  The shooter best known for featuring rescues is probably 1981's Defender, but the mechanic appears in multiple games from this early period, including Lunar Rescue and Stratovox.

The setup of Cosmic Guerilla is confusing, at least as fixed shooters go, but the biggest problem with it is the inefficient use of screen real estate.  The central third of the playing field is barely used and the player spends most of the time squished between the edges of the screen and the bunkers (which are more obstructive than protective).  There would be plenty more shooters bringing the enemies in from the side, but not with a large central dead zone.

Experiment: Alien Behavior

Astro Invader/Kamikaze

Animation demonstrating gameplay from the 1979 arcade game, Astro Invader.  Includes animated sprites of the aliens, player, and UFO.

In Astro Invader, the playing field retains a Space-Invaders-like geometry, but the enemy behavior changes.  Instead of arming them, Astro Invader turns the aliens into falling bombs that leave wide splashes when they hit the ground.  Enemies pile up in chutes before dropping, so you need to clear out as many from the chutes as you can before they fill up and start dropping their alien bug-bombs.

The UFO also makes an appearance, but this time in a deadlier role.  Whenever you see a UFO descending, you need to destroy it before it hits the ground, or else you will lose a life.  This would be straightforward, if not for the kamikaze bugs splashing about.

Astro Invader doubles down on the mechanical nature of Space Invaders, placing the game in a sort of factory setting.  One struggles to even imagine a suitable science fiction context for the action — it feels more like a theme forced onto a game mechanic than a complete experience.  The game doesn’t lack for intensity, and strategy helps, but in the end the mechanics felt so repetitive that I didn’t want to spend time developing one.

Bombs would appear in some arcade shoot 'em ups from 1979 - 1981 (e.g., Balloon Bomber, Red Alert, Dark Warrior), but not in such a central role, so this probably wasn't a very influential game.

Experiment: Multi-wave Shoot 'Em Ups, Fuel/Energy Gauges

Ozma Wars 

Animation demonstrating gameplay from the 1979 arcade game, Ozma Wars.  Includes animated sprites of the aliens, player, and docking ship.

The repetitive nature of Space Invaders was both a weakness and a strength.  It created an addictive experience that people felt compelled to master, but also limited the scope and thematic possibilities of the genre.  Ozma Wars explores the other side of this coin, featuring enemy behavior that is so variable that every playthrough feels different.

Your ship is attacked by aliens of different sizes, shapes and attack patterns; some armed with double lasers, some armed with missiles, and some that spew projectiles all across the playing field.  Enemies follow highly randomized patterns and will appear and disappear unpredictably.  The speed of both enemies and projectiles will vary erratically and some enemies will change their shape mid-flight.

To top it off, the energy meter that determines your ship's life force (lower left corner) gets drained in unpredictable ways when you're hit.   Every collision drains a certain amount of energy, but not all collisions are created equal.  If you get trapped between a pair of laser blasts or in an enemy swarm, that alone could be enough to finish you for the game.

The other downside of all of this unpredictability is that it limits the player's ability to strategize and plan.  The experience becomes static in spite of itself because you learn to expect the random factors and accept the fact that you can't do anything about them other than shoot and hope for the best.

Nevertheless, this ended up being a popular design for shoot 'em ups.  Fuel gauges would be a common feature in subsequent games, as would multi-wave alien attacks.

Astro Fighter 

Animation demonstrating gameplay from the 1979 arcade game, Astro Fighter.  Includes animated sprites of the aliens and player.

Astro Fighter follows a similar model to Ozma Wars, but without quite as much randomness.  Enemies remain consistently visible and their movements speed up steadily as their numbers decline.  There is still a random component to their motion, however.  Here are two examples:

Animation demonstrating the patterns of the aliens from the 1979 arcade game, Astro Fighter.

Both paths have a characteristic pattern, but with a random component that can make targeting difficult.  The aliens on the left all move in unison, but jitter unpredictably side-to-side, while on the right they move in straight diagonal lines that spontaneously change directions.  The resulting swarms look every bit as artificial as you know they are.

However, what's really problematic about Astro Fighter's design is the fuel meter.  Having a fuel meter is not a problem in of itself, but what is a problem is that the player can be (and frequently is) left in situations where they are doomed to run out of fuel no matter how well they perform.  Most frequently, this occurs when you fail to destroy all of the aliens in a particular wave.  In such a case, you will be forced to face another wave of the same aliens, extending the time until you reach the refuel point.  Missing one wave gives you a slim chance of getting to the refuel point in time, but two?  Forget it.  That's a lot of dead game time to hang around a player's neck.

Invader's Revenge 

Animation demonstrating gameplay from the 1979 arcade game, Invader's Revenge.  Includes animated sprites of the aliens, player, UFO, and a missile.

Perhaps the oddest entry on this list, Invader's Revenge is this rare conversion of the Space Invaders machine that uses the original aliens in a game similar to Astro Fighter.  The gameplay is surprisingly complex, including rockets being fired from a UFO, enemies that can steal your fuel, 3d rotation into the plane of the screen, and even a docking sequence.

Enemy motions are fairly simple, alternating between diagonal and side-to-side movements that lack any randomness, but with all of the projectiles you have to contend with, there's more than enough challenge here.  Much like Astro Fighter, it won't hesitate to leave you in a hopeless situation with your fuel level -- if you fail to dock at the end of a stage, you’re pretty much done.