I also dont understand. This is the category of these survivors games (like vampire etc.). Yes, these are related to shooter games, but the classic shoot-em up is going from down to up or left to right. You never come back to the same spot twice.
This is more of an 2D arena shooter, or whatever these types are.
In todays world it seems, the game developers and designer can make only 8 type of games:
- soul games
- fps shooter games (mostly multiplayer)
- strategy games, mostly turn-based
- 3D platformers, that work mostly the same, just with different skins
- some point and click adventure games (quite niche, actually)
- top down survivor shooters that are called shmup games
- racing games (mostly simcade or simulators, here and there some arcade racers, but these are more or less karting games)
- sport games
Oh and not to speak of the roguelite elements in many of these gametypes mentioned above.