Honestly, when I first heard the term “boomer shooter” I thought the games were called that because of the amount of explosions they have. Ion Fury in particular is full of them. It a was a while after I realised that by “boomer” they basically mean “old”.
I think “retro shooter” is the much better term, though “classic” also works.
I started an indie platformer called Archaeogem, early impressions are great. Apart from that today I played Post Void, Donkey Kong Country and Super Mario World.