Final answer:
The PDP-1 was significant for the creation of Spacewar! due to its real-time graphics display, which allowed for the dynamic visual representation crucial for the gameplay, along with sufficient computational power to handle the game's real-time physics calculations.
Step-by-step explanation:
The PDP-1 (Programmed Data Processor-1) introduced several new features that were critical for the development and playability of Spacewar!, one of the earliest digital computer games. Most notable among these features was its real-time graphics display, which allowed visual display of graphic images directly and dynamically on the monitor. This was a significant advancement over the prevailing batch processing models of the time, providing immediate visual feedback and interactive control. Additionally, the PDP-1 had sufficient computational power and memory, which, coupled with the graphics capability, made the complex calculations and continuous screen updates required for Spacewar! possible. The game required the computer to calculate physics in real-time, including the gravitational effects and movement of the spaceships, the torpedoes, and the stars in the background, which was feasible due to the PDP-1's advanced technical abilities.