I came upon this work through an odd path - first Faun brought me its name, then the Saga Project got me listening at work, and then when her reading ended a third of the way through (and just as things were getting interesting), I finished reading it here. It's an story, from which I believe we could steal much.
It starts off really slow, with a distinct lack of mighty deeds of arms. Having an icelandic? woman with a lovely voice narrate this bit was very helpful in getting through it (her pronunciation of the names was also very useful later, when I switched to the text version). A long time is spent setting up the geneology of the hero, which is important because the main conflicts of the narrative are between families rather than individuals. This background turns acts reminiscent of the best D&D murderhobo tradition into worthy deeds of vengeance for wrongs suffered by Egil's kin. Context is everything. The background also nicely establishes that Egil's family's enemies are cowardly and cunning rather than honorable (Hildaleda's sons use slander rather than force of arms, while Gunnhilda uses magic), though the grievance of Hildaleda's sons against Thorulf (Egil's uncle) is also clearly established. They're not evil for evil's sake, which is nice.
There was one battle early in the story that had a good line: "None forward of the mast were uninjured, except for the king's twelve berserks, whom iron bit not." Combat is as a rule quick and deadly, often with loss of life and limb for the losing party. It is also interesting that typically the side that has the moral high ground gains a substantial advantage; that would be a cool mechanic for a game. The troop strengths mentioned are also noteworthy: we see groups of 12, 30, 90, and 300 men. This is about a threefold increase at each step, which falls between Sun Tzu's thresholds for attacking in a pincer (with a 2:1 numerical advantage) and attacking outright (with a 5:1 advantage). In any case, 3:1 is a decisive advantage and likely to determine the battle. Having a retinue size based roughly on one's social status and holdings would be a lot easier than managing mercenaries, too - any respectable landholder can raise 12 men from surrounding farms without promise of plunder, or 30 for raiding. A typical nobleman (or a weak or ill-respected earl) keeps a retinue of 30 men, and can raise closer to 90 for raiding or war. An earl or respected baron with many properties (like Thorulf) can keep a retinue of 90 men and raise closer to 300 for raiding or feasting, but might be considered a threat to the king if he does so, who can raise 300 men on short notice and many more if necessary. So that's straightforward to track in play, and then your mass combat system is that a force outnumbered three to one is defeated unless they have some notable advantage (a terrain feature at their backs or a narrow defile so that they cannot be engaged by all their foes, or surprise or an attack from the side or rear of a formation, or a hero with a righteous cause and a case of shape-strength).
The story's dealings with wealth are likewise abstracted. Some treasures are said to be "great wealth", like a cargo ship full of grain and honey or a beautifully-worked axe. Some are said to be merely wealth, like a fur cloak. If one wanted to run a viking game (entirely hypothetically, of course), it would seem reasonable to track treasure in these categories, and then also to classify treasure as perishable (as in the grain and honey case) or not. Then a sizeable farm produces one unit of perishable wealth for its holder per summer as a baseline, which is enough to feed a family for a year with some leftover for guests and whatnot. A notable baron might have a handful of such farms, as well as fishing or whaling rights to a few places, and so earn an income from his domains measured in single-digit integer amounts of perishable wealth, which he might use to maintain a large retinue or throw grand feasts (thereby gaining renown/status) or exchange for non-perishable wealth like ships or armor (which is interesting in that it never shows up! I do not recall it being ever noted that Egil bore more than a helm and shield for defense; in one pitched battle on dry land it is explicitly noted that he went without mail) or objects of art. Managing one's enterprises carefully (ie, remaining at home through the summer) might cause them to produce somewhat more than the baseline, but certainly less than double, while raiding might produce substantially more wealth and renown in a summer than farming (particularly, one can loot nonperishable wealth in addition to perishable wealth), but also bears the risk of you being captured or maimed or killed or soforth. Meanwhile, commanding a merchant ship and trading lets you convert between perishable and nonperishable wealth at more favorable exchange ratios than can be obtained by employing craftsmen directly, or for goods not locally producible.
At the end of the day the structure of the narrative ends up looking rather like a Pendragon campaign - the characters go on an adventure or two during the summer and then spend the winter at the homes of their allies, telling tales, feasting, writing poems, and perhaps pursuing a marriage suit. Many of Pendragon's cultural values are shared in Egil's Saga as well; duty to family rates very highly, and one had best observe hospitality or risk having one's beard cut off and an eye put out. Men are praised and rewarded for their strength and honesty and vigor and generosity and so forth. But Egil's Saga is much more pragmatic than romantic about religion and madness. While bouts of rage are not uncommon, they don't last the same way a Pendragon knight's passion might consume him whole and reduce him to permanent insanity. Instead, they typically end when the aim of the rage is accomplished, or if the rage were misguided, when an innocent has been killed (how would that be for a mechanic!). Likewise, while piety and devotion to kings play a large part in Pendragon, Egil's family habitually defies kings (to their own peril) and while they may participate in sacrifices to the pagan gods, they're also not averse to taking the "first sign of the cross" in order to be able to trade with English christians (in accordance with English law at the time). Most mentions of gods come up in the poetry rather than in actions taken by characters; prayer is almost unheard of. Perhaps it was so common as to go unmentioned implicitly; I don't know. So as much as Pendragon's traits / passions system is very cool, it feels like a poor fit for modelling Egil's Saga; the vikings are too calm and collected (there's a sentence rarely uttered...).
They are in some cases very stubborn, though, about what they believe is rightly theirs, to the point of multigenerational bloodshed. "Enough to live on" is not really a concept recognized by Egil and kin in these matters - if an old man died and your wife was to inherit half of his lands, then your family shall have them regardless of your current wealth or how many people you have to kill to get them. They are rightly yours, and to fail to defend your rights is cowardly and unmanly I guess. It sets one up as a target for ne'er-do-wells who might further infringe on one's rights, and causes one to lose face among one's peers. On the flip side, they're also not a stingy people, and readily give gifts of land and furs and poems and such to those who do them good. Sort of a romanticized violent libertarianism I guess, when men would die to defend their rights against kings, though you might have to ignore the raiding and the enthrallment.
Other interesting things about the narrative structure: for covering a couple hundred years, it's very short! Sometimes things happen like "and then he went sea-roving for a summer, and failed to find any good booty, and then he stayed with Arinbjorn for the winter," and most of a year passes in a single sentence. Characters pop in and drop out with little notice, but often some backstory ("He was the son of so and so who was the son of so-and-so, and so was Egil's kin"), and then stick around for a chapter or two and then are never mentioned again. The poems rather grew on me, and it would be a funny game mechanic to get bonuses for composing probably-terrible poems in the viking style. Two named weapons appeared! Neither really lived up to my hopes for them, unfortunately. The viking travellogue bits were neat. Their journeys take them throughout Norway (sometimes in confusing details for one unfamiliar with the region), into Finland, Kvenland, and Bjarmaland (now part of Russia) in the east, to Denmark, Holland, and Flanders in the south, and to England, York (or Jorvik as once it was called), and of course Iceland in the west (again in confusing detail, though it is kind of cool to be able to look at Google Earth and go "OK, so that would've been right about thereish?").
Anyway. Woo vikings! Maybe I'll read another saga this weekend.