For those unaware, the current Bundle of Holding is for Runequest 6 and some supporting material. This is somewhat fortuitous, as I was just looking into RQ last weekend, and lo! Opportunity knocked.
So far I've only read the core book, and it's interesting. It is very clearly from a lineage of games which I have not met before. Chargen is classless, with culture and profession determining starting skills but not determining the path of further advancement. There's also quite a bit in chargen on family and passions (basically allegiances; I dislike the word passion, but that's me). No feats to speak of really, except for one special ability per fighting style, and skills are on d%, with a base value determined as the sum of two ability scores (ex: your base value in Athletics is your Str plus your Dex, each of which was rolled on 3d6 during chargen), and improving incrementally from there (so ability scores give you a higher starting point, but that's it). Difficulty modifiers to skills are handled as a multiplication of the skill value (so an extremely easy task with a skill where you're rated 50% is doubled to 100%, or a difficult task might multiply your skill by 2/3, for an effective rating of 34%), though a straight subtraction / addition system is also presented for those less mathematically-inclined. Critical success and failure is a thing for all skills, and honestly a fair chunk of the skills chapter goes into describing the sort of results expected from crits on each skill.
The fatigue rules look sort of important but also a pain in the ass. Their economic numbers look sort of suspect after playing ACKS, but that's to be expected I suppose. Combat is a peculiar mix of gritty realism and cinematism. On the gritty side, you have hit locations with their own (low) HP and armor values, maiming, bleeding to death, parrying / defender gets to roll for defense, and high-power characters dying to headshots from lowly orcs with taken by surprise or surrounded (protip: wear a helmet). On the cinematic side, there's this notion of special effects in combat, which cover everything from throwing sand in their eyes to Boromir-grade arrow impalement, and which are generated by beating your target's (or attacker's) opposed roll to hit or defend by certain margins. This is sort of neat, because it removes the necessity of specialist one-trick maneuver fighters that appears in D&D. Since you get to choose your effects during combat, though, I could see this causing a significant performance hit. A cheatsheet or quickref card is probably out there for these, and seems vital for rapid play. I like their action point system (resembled Codex Martialis', but not as steep of a slope) and their fighting style rules, though.
There are five distinct magic systems in the core rulebook, and they each work slightly differently. Folk magic is low-power utility stuff that hedge wizards might have access to. Animism deals with binding and making deals with spirits and adventuring in the spirit world. Mysticism is entirely personal enhancement via focus; very good for the eastern "monks and ninja and samurai" sort of game. Sorcery is sort of traditional high-magic arcana, though it does some simplified True Sorcery-esque things that I like. Finally, theism is magic drawn from deities; it produces more powerful effects than the other schools, but has its own more limited magic point pool that can only be recharged by worship in a consecrated place. None of these systems resemble Vancian casting in the slightest, and I expect they'd provide some interesting contrast within a setting; elven animism vs Izradorian theism in Midnight, for example.
There's a significant focus (and a whole chapter) on building magical traditions and the cults and brotherhoods surrounding them. Most traditions only get access to a handful of strongly-themed spells, and learning them requires significant effort to earn access to the organization's secrets. Not at all a "well I levelled, now I learn two spells of my choice from the whole list" sort of deal. As players from my Shieldlands game well know, I love me some cults as adversaries for PCs, so this is fine by me. It also provides a lot of room for differentiation between schools within one flavor of magic; going back to the kung-fu movie game, one could easily cook up a bunch of different unarmed fighting styles, each practiced by a monastic order with accompanying philosophies and traditions.
Finally, there's a critters chapter that I skimmed and a gamemastering chapter that I read very late at night some days ago. It was standard DMing stuff. Not at all simulationist / no worldbuilding advice present. No challenge rating-equivalent mechanism, but DMs are provided some loose / common-sense advice on how to construct balanced / challenging combats for their players.
The book is not well-edited, and some of their word choice is objectionable (they appear to use "whilst" about six times as often as "while", for example). Semicolons are frequently used in place of commas. At one point they refer to the city of Meeros as Meereen instead (Meeros is their creation; Meereen figures significantly in A Song of Ice and Fire). The art's in a black-and-white pencil style vaguely reminiscent of Iron Heroes, but without the themes of grotesquery and savagery that pervaded IH's artwork. I find the name "Runequest" somewhat ridiculous, as I do most proper names containing "quest", especially given that the runes don't appear to be all that significant (in this version at least). The font they used is not great, having lots of extra little bits and whatnots, which are slightly distracting.
In some ways it's a lot like the homebrew classless skill-driven systems I worked on in high school, but given an extra couple of decades to mature. It feels sort of reactionary to D&D in a lot of ways, particularly in how it addresses a number of complaints I've heard from first-time D&D players (charging should make your attacks less accurate, ablative hit points are a terrible abstraction, Vancian magic resembles no magic system they've ever met, why can't I dabble in a bunch of unrelated skills, why can't I parry, why is skill X based solely on stat Y, and so forth). I dunno. Might be something to fiddle with solo for a while and see what I think of it after that. Some work has been done on an Elder Scrolls conversion, which the system seems like it would be a great fit for.