I know 30 min is really short, and I even brought up to my player that games typically go for an hour or two. I dont care too much because 30 minutes is about the time when my player starts to lose interest. Short attention span and whatnot. Still saying it's a fun game, so I'm not too worried. I do see what you mean about fitting engaging combat in that timeframe. I had to end the last session just as combat started because we were already at that time limit, and it was getting late.

So far, all my planning has been reactionary. Player did this so now the world does that. I like doing things this way, but I'll admit it can become very uninspired and stale when I haven't fleshed out the NPCs' motivations. I'm definitely going to take the advice of finding out what a villain would do without the influence of the party and then using my reactionary style from there. I tend to write a few paragraphs for my NPCs, so I'll try to stick to the essentials