I asked for PF because it seems popular here. If not that, what other D&D-esque games would you say are suitable for one-on-one role-play?
OSR games would allow it, if the GM is following the assumed playstyle. That means reliance on hirelings and followers, sandbox without assumptions about the plot, the main source of XP being different from fighting or at least not requiring fighting, and lots of random generated events, both in fights, travel, or in character generation. In fact, the player should be aware that fights are, like everything else, inherently unfair. This means that if you're into one that you didn't resolve with planning and improvisation, before it started, you've obviously screwed up
! And yes, I mean the approach "combat as war" prevails here.
Make no mistake, OSR characters start out badass, and get from there. The first level fighting man is called a Veteran, with the title Hero being a single digit of levels away. The green troops don't have class levels, period. It's just that you don't want to risk, because the GM might have rolled an opponent several levels above you on the random opponents column, and you don't expect fudging neither in your favour nor against you...
On top of that, OSR games tend to be free in PDF form.
And yes, done well, it's much closer to FATE, Sorcerer and In A Wicked Age, or even to Runequest and Traveller, than to standard D&D 3.5 or Pathfinder. The changes in playstyle between editions have been striking, to say the least.
Speaking of which, if the above doesn't appeal to you, why don't you actually try FATE or FU? Both work just fine for solo games.
And then there's the Trollbabe game and S/Lay w/Me, which both assume a solo game. Kinda the opposite of the party approach exhibited by modern D&D at least since 3.0 and probably since late in the AD&D2e times. S/Lay w/Me also has the advantage it already assumes games can veer into E.-friendly territory.
I mean, it's a game where the GM plants a Monster and a potential Lover from the get-go in the setting. The two might be the same thing, or not, and one of the main questions is whether the character gets together with the Lover. It's kinda surprising we're not seeing more games of it around here
I've had quite a few good experiences with 3.5 and pathfinder solos, but I tend to play either full spell casters or a race that gives me good SLA's so that probably biases things a bit since I could handle any sort of encounter with a little thought.
That probably explains it. These are the two options I ban if I'm running a d20 game, and you can't get me to play them.
I general I do agree with Thufir if you're going with more traditional dnd adventures. I don't think it would be much of an issue if the system was a backdrop for the role-playing where the actual mechanical portions are focused on things the character is able to accomplish, or not accomplish if that's the goal of the game. See a rogue getting missions about infiltrating and stealing things or assassinating someone wouldn't be so bad, but a traditional dungeon crawl might be very painful for them.
I agree as well. That's also why I think he doesn't need something with so detailed rules as Pathfinder.
BTW, a "traditional" dungeon crawl, meaning an old-school one, would be quite possible. But it would require a high level of skill on the part of the player and thinking around the system. Or if you prefer, roleplaying details instead of resorting to the system. Personally, I prefer roleplaying and then resorting to the system for adjudicating the consequences, but that's a matter of style.
As for specific advice on dnd.
A bunch of the options are are rough, but able to be dealt with for parties are pretty devastating for a solo character in my experience, ability damage/drain, grappling, and negative levels coming to mind first.
The usual dnd action economy issue is inverted with the player taking the role of the boss monster unless they have summoning or allies. NPC allies are really nice to help deal with the problem.
Consumables are great for giving characters ways out of problems without making them permanent additions to the character.
Agreed on all counts. And grappling also tends to be boring in a solo game, unless the characters are really into it.
The primary other systems that I've found work well for fantasy solos are Exalted and Mage. Simply due to the versatility that characters can come up with fairly easily in them. I suspect Vampire and a fluff-modified Shadowrun would also work well.
With the caveat that Exalted, as a system, doesn't work well neither for group nor in solo games, I agree. That said, it's a great setting for solo play, which what I suspect you meant.