For those who have seen my “How To Get Started” page on this site, you already know that I like to cultivate a diverse range of games. I am not as dedicated as some collectors (my RPG library only fills two shelves, of which I mostly only play the top shelf), but still I like to have a few solid picks.
Today I wanted to go over in my opinion the most important way to cultivate an RPG collection:
“Uniqueness.”
In the form of mechanics, setting, Feel, accessibility, and more.
I have made clear in earlier posts that I prefer unique RPGs above ones which are cozy and familiar. I can no longer keep track of the number of fantasy RPGs I have seen which are one or two small rule changes away from total similarity, meant to evoke the spirit and “dungeon-battling” fun of early D&D books. Often it is presented in an entrepreneurial spirit, trying to even recapture the trail-blazing nature of AD&D. However, that is no longer the world in which we live.


As such, I strive to populate my shelves with books which are at least passably different or interesting. And if I have around 3-5 books (depending on how you count settings) which are “fantasy adventures,” I will be the first to admit a small degree of hypocrisy in regards to my comfort zone.
My books have to at least do something well which none of my other systems do.
Examples are always fun, so here’s a few hand-picked ones:

It’s such a pity that this system can’t be easily found these days. It was used in the Firefly RPG and Demon Hunters, but seems to have dropped off in popularity.
I own Cortex Classic because it does GURPS’ character creation system better, and it has some really strange probability curves due to the dice combinations (d4 + d10, d6+d8+d2, etc.).
It’s also decently deadly, which I find always makes for good roleplaying. Higher stakes means character survival is more exciting and rewarding most times.
Mouse Guard is in my collection for many reasons, but two most notably:
1: The most universally adaptable conflict system I have ever used, which is a great combination of strategy, character skills, and roleplay.
2: A character sheet which is only 5% directly related to fighting and killing, as opposed to 90-95% like most systems (Looking at you, D&D).


Shadow of the Demon Lord is fast and efficient in pretty much every aspect. The book is one of the most clearly organized I’ve ever read, character creation takes 5-10 actual minutes if you know what you’re looking for, and the Boon/Bane system of difficulty is incredibly clean.
The setting is also one which really tries to push the boundaries and create something that feels like a truly dark fantasy world.
I’ve heard it said that this RPG was designed so it could be run while drunk, and I can see how that is the case. These rules are great.
And I’ve already ranted about how Vaults of Vaarn is great.
Generally I’ll go for simplicity these days. I rag on Eclipse Phase a lot for its rule set, but only because I think the setting is so great and the mechanics used to bring it across are just not smooth enough. Remember, this is a hobby about immersion, and anything which can be done to make things more immersive is a step in the right direction.