This is definitely mechanically similar to 80s arcade and Atari games. I think that, overall, you've achieved your goal which is easily the most important part of Ludum Dare.
Unfortunately, that doesn't necessarily make the game very much fun.
Paddle motion could use some acceleration, both to give motion more weight and to allow finer control over small motions.
The slow projectile speed coupled with the 1-bullet allowance makes missing excruciating--and while this encourages deliberate/efficient player action, deliberacy works best with more cerebral games than simple action ones.
There didn't appear to be much variety in treasure velocity on a moment-to-moment basis (maybe it was increasing steadily over time?). If treasure fell at varying speeds, it would make the player's decision making more dynamic, since the priority of actions they can take would shift. As it is, the slow treasure speed means they can be pretty safely ignored until the last moment.
So, congratulations on creating a pretty authentic-feeling Atari game, but I think it needs a few tweaks to be a fun game.