The Difficulty in Space Invaders, Galaxian, and Galaga

by: Zippynom

            The early days of popular gaming were in the arcade. Here, difficulty was money. The more difficult a video game was, the more coins players would spend to try again. The majority of video game developers would make design decision that made video games more difficult to play and easy to try again. Usually a player would start with a few lives and play to the end of a number of levels. They could get a high score from points won by defeating enemies or collecting bonuses. After a player lost all their lives they would often be asked whether they would like to insert more coins to start again, sometimes retaining their current progress. Players were encouraged to get better at the game itself so they didn't have to spend so many quarters to beat a game or get a higher score.

            Space Invaders was developed by Midway Games and in arcades by 1978. It was one of the earliest games to be released on a large scale and quickly became very popular. The gameplay of Space Invaders was relatively simple. The player would control a ship that could move side-to-side near the bottom of the screen. The player had to shoot upwards at the invading aliens whom would slowly shimmy down to the bottom of the screen. If they reached the bottom, the game was over. The challenge was in the player lining up the shot so it would hit an alien. Only one bullet could be on the screen at a time, so the player could shoot aliens closer to the ground more quickly, however a miss would cost time that could otherwise be spent shooting more aliens. As more invaders were shot down the others became faster. There were 55 aliens per level, and each level was the same except for the aliens being a little faster. Aliens gave between 30-50 points per kill. Occasionally a difficult to hit bonus ship would fly across the very top of the screen. If the player could hit it it would give 50-300 points. 1,500 points gave an extra life. Four bunkers stood between the player and the aliens that would block both the player and alien's bullets. These bunkers gave the player some cover and would take damage over the course of a game until they were destroyed. A common strategy was to shoot a small hole through a bunker and hit the aliens through it. Space Invaders was a relatively easy game as long as the player could kill the final few aliens of a wave quickly, before they become too fast. Space Invaders was the simple foundation that the following successors would be built on.

            Galaxian was released by Namco to Japanese arcades in 1979. It improved on its predecessor Space Invaders in many ways. It had color and the enemies moved in more advanced patterns. As in Space Invaders the player would shoot up from the bottom of the screen at enemies that fell from the top of the screen. What was most obviously changed were the losing conditions. Instead of moving slowly down the screen, the enemies would drop bombs and make suicide runs against the player, whom would lose lives when destroyed. This was definitely an improvement of gameplay, as the player now had more direct control over a loss. Though the difficulty in Space Invaders had been limited to the speed of enemies and the rate at which they fired, now Galaxian's enhanced software and hardware allowed for enemies to literally behave more aggressively at higher levels throwing more bombs and moving faster. One hit would kill an enemy, and one enemy bomb or collision would kill the player. Enemies were worth 30-100 points, depending on their height in formation, while command ships were worth a most 800 points. This time it took 7,000 points to get an extra life. Once again only one of the player's bullets could be on the screen at a time, and a miss still cost valuable time. Galaxian, without the defensive bunkers or predictable enemies of Space Invaders, is arguably more difficult than its predecessor. It requires more precise timing and aiming of a shot than Space Invaders due to its speed and the diagonal paths of the enemies.

            Galaga was the successor to Galaxian and it again enhanced the Space Invaders formula in almost every way. Enemies were once again faster and smarter, and there were more of them. At the beginning of each level the enemies would file in from the top of the screen rather than just appearing from nowhere. This gave the player time to pick off a few enemies, but sometimes a few enemies would unexpectedly fly right at the player. Levels were much more dynamic. Enemies would travel in different paths depending on the position of the player, spinning and whirling in space. They would often dive at just the right time to catch the player off guard or attack from the side where the player could not shoot them. After a certain number of levels there would be a bonus level where the game changed the rules a little. Instead of a horde of enemies assembling in formation and making strikes at the player, a bonus level would have the player shooting at enemies while they buzzed around the screen in various patterns. If the player could shoot all of them before they left the screen they were rewarded extra points. The most interesting difficulty mechanic in Galaga, however, involved the sacrifice of one of the player's lives. An enemy command ship had the unique ability to capture the player's ship. The captured ship then became an enemy for the player's next life. If the player could destroy that enemy command ship they could get their old ship back in the form of an attachment to their current one that would fire two bullets at once!

            Galaga can be considered more difficult and complex than both of its previous iterations, and it handled that difficulty very well. The concept of risk is reflected throughout the game. The player, after losing their ship to the commander, was now pressured to be skillful enough to retrieve the lost ship. Enemies are worth more points if you shoot them while they are traveling down to attack you and the player had a chance to shoot some enemies while they got into formation at the beginning of a level if they could dodge the kamikaze ones. Finally, the bonus levels gave the player a chance for more points if they were skillful enough. Galaga is a great example of difficulty handled well.