The more media you expose yourself to, the more metaphors you can apply to the gaming experience. In movies, some inspirational people are Spielberg, Hitchcock, George Roy Hill, Rob Reiner, and now Sam Mendes. Also a big fan of Chuck Jones, who directed Warner Brothers cartoons. Gateway, Ender's Game, Snow Crash, Hitchhiker's, so many more. Lots of sources for inspiration indeed.
Conversations can range from some conversation trees to just one line.
Sometimes you have to be the right person Each character has a World Skill that is unique. Sly can pick its lock. Sly's robot lackey can interface with it. It can be difficult to maintain focus on a project this huge, simply because there are so many areas that need tons of attention. It's sort of like making three or four games at once.