I didn't know this was a thing. I collect what strikes my fancy between the systems that I own. There are some series that I like. There are also some publishers I like. Out of my Famicom stuff, Konami is the second most represented "category." The first being pirate carts. I also do hardware a little bit. With NES, it really is a "grab what I like" scenario. I get rarity, obscurity, focused collecting, I just don't do a lot of it anymore (I had to move a few years back, and sold a lot of stuff to help come up with the funds. It was an emergency situation). I've probably done more rarity based collecting for Atari 2600 than the other systems, with only a handful of carts that would be called rare on NES/FC, SNES. Uncommons I think mostly. Maybe as space becomes available, I can do something like that again. I kind of want to focus on some of the neat hack/homebrew/translations that are circulating around right now.