Without a doubt this was quite likely a prior topic years ago....
And I would have answered Kaboom! without a doubt - until recently.....
M-Network's Astroblast just simply ROCKS with a paddle controller. And I do mean ROCKS!! I would go as far to ask.....Name a better shooter for the 2600!
With the auto-fire feature and a decent paddle controller this game that I just recently acquired deserves some serious consideration for best shooter. 25 years too late but glad I found it!