A strange little side quest
The fun part of looking behind Earth Defender Html5 is seeing how many older ideas are still alive in modern play. The Moon orbits Earth at an average distance of about 385,000 kilometres, and surface gravity there is roughly one-sixth as strong as Earth's. That old idea kept changing rather than disappearing. Doom changed game design and distribution in 1993 by separating its engine from content and spreading widely through shareware. That long chain of experiments is part of why space still feels fresh when a game finds the right twist.
