Recently, the tinkerage picked up Strider Mode, the solo rules for The One Ring RPG. Strider Mode, as you might think, contains rules for playing a single player-hero in Middle-earth, adapted from the system of The One Ring.
Now, The One Ring Second Edition is a fine system with many thoughtful and atmospheric touches, but it still isn't the game I would choose to run adventures in Middle-earth. As per my review of the first edition, the system is still too programmatic and committed to phases and counters of all sorts. It feel sometimes as if deep down it's a board-game, where your character's engagement, reactions, and choices are shuffled off to dice-rolls on a table. As readers might gather, my instincts for gaming in Middle-earth are either to strip everything back to a free-form core in the style of the Green Dragon, or to use the clean, flexible structure of Basic Role-Playing.
Strider Mode, on the other hand, is a great resource for playing through a solo Middle-earth experience. It contains two elements that are essential to solo play (and darn useful for group play also): a chance resolution system and a semantic generator.
By a chance resolution system, I mean a way to pose the question how likely is a certain thing to come about, roll, and resolve that question. In Strider Mode, that's a d12 roll ranging from a "certain" chance to an "unthinkable" one, with an extreme result on either end. I often use the same sort of roll to determine the severity or intensity of a certain condition, so a low roll is hardly at all and a high roll is extremely so. This can range from the friendliness of an inn to the severity of the weather on a given day. And chance resolution also provides a basic action resolution system, as you can check whether, given current conditions, a character's action is likely to succeed or not.
What I call a semantic generator is the "oracle" in other systems. The semantic generator allows you to randomly generate words or phrases that you can use to attribute meaning to an uncertain or open situation. Strider Mode calls this the Lore Table. In my play all the books approach, this would be the library of tables and generators that you can call on to frame an otherwise open encounter or scene. In fact, as you travel in Strider Mode there are "Event Detail" tables that provide descriptive seeds for events along your journey (from mishaps to chance meetings), as well as the atmospheric lore tables which suggest the Action, Aspect, or Focus of the moment.
These two tools provide the adventure and discovery for the player that the GM's preparation or the written scenario usually deliver. If you lost your way, did you stumble on a ruined tower or a bandit camp? What is the tale of that ruin? The task for the solo player is to deliver these questions to the dice and then play the options they suggest.
As I mentioned before, I don't use the core rulebook for The One Ring for resolution, but rather a free-form approach using the chance resolution system. Of course, there's nothing wrong if you enjoy using the published rules and engaging with the variables of the full system, but I find that a lighter, more adaptive system allows me to engage with the scenario at hand rather than the intricacies of the rules.
One might think that this adds another kind of challenge, switching between the GM's mindset of making assessments and calls on the fly and the player's mindset of responding to the action without the support of firm procedures. This isn't what I find. Consider that even with a complete "system" in play, the GM or the scenario author has already prepared the encounters and considered the modifiers and relative difficulties, and this means neither setting dead-end tasks that are too difficult nor challenges that are too simple. All you need to do to GM yourself is be open to the chance of success and failure, which means that you sustain the uncertainty and hence the drama of the moment, and estimate chances fairly. For any given roll, there's always a chance of a wildly high or low outcome; and if you're rolling for yourself, that wild result is bound to come up. Finely-measured probabilities are not really required. And as Hickman et al observe, in the end it always comes down to a probability, assessed as a number on the die or dice that is constrained to a given range. Call it fairly as you see it, check the result, and keep going.
In my test of Strider Mode, I found myself bushwhacked by bandits in an abandoned farmstead, trading words with stiff-necked dwarfs, and battling orcs and a cold-wyrm in a ruined tower. The Lore Tables in particular do a good job of pushing your to engage with Tolkien-like tropes and challenges. For something that's either in one's own head, or in the dice and the tables on the page, that's a pretty good trip, alone, across Eriador.