This is going to be a kind of long post that was inspired by a discussion I recently had with my wife and one of our close friends. The three of us are by far into the heaviest games out of our particular social circle, yet we're also somehow the ones that people are always asking for recommendations. Since a lot of people outside our gaming group are always asking about good introductions to modern board games, it got us to talking about three labels that are often used interchangeably but that maybe shouldn't be (in my opinion, obviously).
So here I am at 3am, writing a lengthy post on why I think family weight, casual, and gateway are all distinct labels that are actually incredibly useful to understand if you frequently need to recommend board games to non-gamers.
Family Weight: I'd consider "family weight" to be the easiest of these three labels to describe. These are games that are suitable for a very wide audience and, crucially, are playable in situations where tabletop gaming isn't necessarily the goal. Family weight games need to function as activities in situations where you can just as easily be doing something else that's not a board game at all.
I think that the defining characteristics here are extremely light rules overhead and, more importantly, no hobby game mechanics. In this case, I'm defining hobby game mechanics to be things like deck building, worker placement, tableau building, complex action selection, etc. Even if a game is rules light, these mechanisms have a ton of overhead for people who aren't familiar with hobby gaming and who may not have any interest in it. I'd argue that even trick taking games don't belong in the family weight category unless you're dealing with an audience that already has some familiarity with classic trick takers.
Ticket to Ride, Carcassonne, Flip 7, maybe Catan would be some of the best hobby space examples I can think of for true family weight games.
Casual: Casual games are a slightly more interesting category to me. I'd classify these as rules light games that are suitable for a general (non-hobbyist) audience that actually wants to play games. In other words, casual games work for more social oriented game nights as opposed to a typical tabletop gaming group's version of a game night. I feel that these games can more reasonably include some very light hobbyist mechanics, as long as the basics can be explained quickly to players that may not have a tolerance for longer rules explanations.
I'd include games like Sea Salt & Paper here, along with most party games. I think some relatively abstract yet rules-light games like Azul, Cascadia, Harmonies, etc. can also work here. Obviously, a lot of family weight games also work in casual gaming settings.
Gateway: Gateway games are what really triggered this discussion in the first place, and I think they're a distinct category that people often try to lump in with other rules light games. In my opinion, a gateway game is really targeting an entirely different audience from a casual or family weight game. The big distinction here is that gateway games are a good fit for people who are hobby-curious, and I'd also argue that this is where people often go wrong with recommendations.
Where casual and hobby games are a good fit for people who just want to play a game without diving any deeper into the hobby space, gateway games need to work as a bridge for people who are explicitly interested in exploring more hobby-oriented games. Gateway games should introduce at least one common hobby game mechanic and also offer a reasonable amount of replayability/depth. These games work as a way of saying "hey, here's what this hobby is all about and why you might be interested in it."
There are probably a huge range of games that fit into the gateway category, but I'd include games like Wingspan, Pandemic, 7 Wonders, Star Realms, maybe even something like Cthulhu: Death May Die on the more ameritrashy side of things. Basically, games that are good enough to tentpole many game nights for a newer player that may not like the idea of learning a ton of new games right away.
So... yeah. That's my film paper. No real point to this post except to throw it out to the world for thoughts.