“Bro Explaining” is a meme format where a guy is enthusiastically preaching about a subject to a clearly uninterested woman, in this case transposed to a Space Marine spreading Codex Astartes lore

If you’re really looking for not-catch-all systems

I’m not, but don’t let that get in your way of reccomending good stuff that you enjoy playing. There’s nothing wrong with taking a free opportunity to talk about games you like.

Even a bit later, sometimes. From “Snow Crash”:

Until a man is twenty-five, he still thinks, every so often, that under the right circumstances he could be the baddest motherfucker in the world. If I moved to a martial arts monastery in China and studied real hard for ten years. If my family was wiped out by Columbian drug dealers and I swore myself to revenge. If I got a fatal disease, had one year to live, devoted it to wiping out street crime. If I just dropped out and devoted my life to being bad.

Hiro used to feel that way, too, but then he ran into Raven. In a way, this is liberating. He no longer has to worry about trying to be the baddest motherfucker in the world. That position is taken.