Both graphically and audibly, this is clearly Defender.
All the craft are here -- pods, swarmers, baiters, landers, mutants. You can
accidentally kill your fellow humanoids (an important gameplay mechanic that was
omitted on the 2600 version), and the radar and mountains are there just like
in the coin-op. The frame-rate chugs a bit at times, but it's funny how we
never noticed frame rates back in the 80's! The screen is literally filled
with action and particles, it's very intense, as it should be! Sounds
are as close to arcade as possible.