I'm curious if anyone can has and can share their "rules" when trying to categorize games into different style...
For example, Super Mario Bros is a platform game. It scrolls and the main play mechanic is jumping around across gaps, on platforms, etc.
So what's Mario Bros? There's jumping and platforms, but no scrolling. It even pre-dates the time when we started using the term "platformer". (OK, bad example considering I would classify Mario Bros under my "retro classics" list, but you get the point!)
Now what about Shinobi? It's also a scrolling game where you can jump up and down some platforms, but you can shoot ninja stars and slash with a sword. Is this a Platform game? Or is it a Beat-em-up? I've even seen these kinds of games classified as "shooters" because you can shoot a weapon.
Fighters. Are they strictly one on one or can they be scrolling? Does that make Fighters and Beat Em Ups the same category? Now what if the character has a gun?

Are you getting dizzy yet?
~Ray B.