Avenger (Turbo CD) - Under Defeat's under-rated, and great, TCD predecessor

[A Black Falcon]

Well, shmups are usually broken down into the vertical-scrolling ones and the horizontal-scrolling ones, but both are kinds of shmups, so I'd say they are the same genre... but yeah, those are the two main categories of the genre. A few games have both directions in them (Life Force/Salamander, for example, or Axelay), but most stick with one or the other.