I've just started a Planescape game for my BF. I tried to run him a Planescape game once before, a two years back, but he didn't really take to it, finding the sheer amount of weird too overwhelming. We've got a new system in tow now, and with a new Player's Guide for that system, it seems to have suddenly clicked in his mind as Fun rather than Bewildering.
Lucky me. :) I love Planescape and have wanted to run a game set there for ages. It's the kind of setting where anything can happen, where I can introduce just about any villain or location or adventure that I can think of. To make things easier on the both of us, I've limited our adventure space to the Outlands, a large area including a city of paladins, the realm of the Celtic gods, and walking towers, but still an enclosed area for us to explore first.
In any case, I'm actually feeling wildly optimistic about this game. BF is really into it (he has a wavering attention span, so this is important) and it's an easy setting to use to help me improve an area of GM-weakness I've got because it encourages roleplaying and bizarre happenings.
I understand the whole "yes and/but" philosophy of GMing and try hard to stick to it; easier done, as I've only got to watch after one player's random schemes and plans. Letting BF try to interact with the game world (even in ways I hadn't considered or I initially wrote off) keeps him invested in what's going on, challenges me as a DM to think about what happens next, and keeps the game moving forward. He doesn't get to automatically succeed on everything he does, but his attempts have an effect on the game world, even if just in small ways. If he wants to convince the Red Knights that they should swear loyalty to him, then he can; now the Knights are divided because some didn't want to follow him, and he has a group preaching against him/harrying him/joining with his antagonist, but he also gets some Red Knights to help him protect his home kingdom.
Lately I've been focused on trying to make failures as dynamic and interesting. When I first started gaming my GMs ruled failures to be as flat and miserable as possible; if you try to sneak up behind a guard and jump him but the roll is low, then you stab yourself in the foot accidentally; if you try to sweet talk the princess but fail the diplomacy roll then you suddenly forget words and start drooling. It was sometimes amusing, but mostly it served to discourage the players from trying anything. Plus, it established the idea that we were incredibly incompetent, because why else would seasoned veterans spend so much time dropping their weapons on their feet? Overall this method of "no, and you're also a loser" actually worked against what these GMs claimed they wanted in their games, disrupting the atmosphere and keeping us from getting involved in the story.
So I've been trying to make something happen after a failure just as it would a success--and I had my first real "light bulb" moment last session. BF had just entered a new city and decided to make a haggle roll to find a good inn for the night, but he rolled very low. I had expected to just make up a nice inn for him but suddenly that didn't seem to match what the dice had in mind, so I declared that BF's character wandered the trade district for an hour, unable to get directions as he made various cultural missteps in his dealings with the natives, until finally stumbling upon the last inn that would take him, the Bed and Food. The insides were sparse and dusty, with one painting of a wilted flower for decoration, and the food was dry and bland. The innkeeper was a very eager but obviously overwhelmed dwarf. Rather than just end there, with him feeling bad about rolling low, I decided to have the innkeeper talk with BF's character. The innkeeper explained that he had been an accountant but took over the family business when his father fell ill, and didn't understand why his straightforward attempts weren't attracting customers. After some back and forth BF brainstormed some ways the innkeeper could improve his business--and then the dwarf offered BF free food and board for the rest of his stay in the city, so long as he helped him redecorate and find a new cook. BF was super jazzed at the end of the session, and I was pleased that I had managed to generate a mini-quest out of his botched roll.
Fingers crossed for next session. I'm going to use the Bed and Food inn to help introduce some characters (like a money-grubbing ooze mephit) and help wrap up the issue of the trade caravans being attacked.