Space Invaders is one of those games that when played, causes the player to feel that he has the responsibility of fighting for his life against a relentless foe. The player assumes the role of John Cage, an innocent dove who is being pursued by scores of hostile aliens who are intent on taking over the fragile peace on earth. To achieve success, you need to build your space ship to the maximum extent possible and employ all the strategies that are necessary to outwit and outfight the enemy. When you play the game, the screen will scroll rapidly across the bottom of the screen, forcing you to react to the situation as fast as possible.
Space Invaders is simple by today's standards, but back then it was a major technological breakthrough in its time and to achieve victory against the space invaders, the player had to build his craft to the utmost extreme. Typical levels usually feature a single player shooting invaders with a powerful laser gun while using various shields to deflect enemy fire. Sometimes the goal of the game is to destroy all the space invaders before they reach the end zone, where the other players can continue shooting at the space invaders with their laser guns or with their other tools. However, if you are playing Space Invaders with two players, then sometimes you must split your attention between the two space invaders to successfully accomplish your mission.
In addition to the standard goals, there are many secrets and power-ups which can be used to make the game even more exciting. For example, in the classic Space Invaders game, the player only needs to hit his enemies once to win the game; however, in the two-player versions, you must find the best way to beat your opponent and defend yourself with the power-ups available to you. These include the following: freeze, which slow down time to allow you to attack safely; death, which cause the alien spacecraft to disintegrate when it reaches the end of your screen; and indestructible, which prevent the alien spacecraft from returning to its rightful place on your screen after you have defeated it. Although there are many more power-ups available, these five are by far the most useful ones.