At least, i think that is the term for these games, I literally adored them when i was a kid.
Recently i tried 2 and was blown away both visually and well uhm reflex wise, not to mention all the options you have these days. Turret motions, weapon load outs and who knows what else. In Cygni i have yet to blast past the first level, in R-type i managed to venture a bit further, on kiddies mode that is. I imagine people who play these games are also excellent efighters though who knows.

Leaves only one question

Top Down or Sidescroll ?

**warning the screenshot taken from the opening from Cygni might be considered shocking