Hey all, just my 2 cents, but first off,, GREAT JOB on this!! I'm DL'ing it now to try it out. I also just got into Descent. I LOVE it and am playing it solo. Here's the thing about Descent, it lends itself pretty easily to "playing both sides", and still not interfering with rooting for the heroes. Here's my approach, and what I've found that might help out. Now, this might sound a little nuts, but hell, were gamers right? When I started soloing it, and learning the rules, I plopped my D&D Balor figure (google that mini and it looks like a wicked a$$ overlord BTW) next to the overlord deck! On the overlords turn, I pick up the overlord cards, and figure, if this Balor figure was a overlord, what would be a few HIGHLY logical moves he would do, to waste these heroes. I find maybe 2 or 3 REALLY great moves on the overlords turn, then assign them to a D6 and roll. For instance, on a roll of 1-3 these goblin archers are going to stack up, and commence a full assault on 1 hero, 4-6 these goblin archers are going to go for a quest related object. So in a way, it's an A.I. on the fly for the quest I'm trying to beat, or situations that arise. So you really don't "know" what the overlord will do in a sense. For overlord cards such as "tripwire" and others of the such, where they have to be played when a hero moves, I play with this rule: Everytime a hero moves as 1 of his actions (without using exertion) I roll a D6 on each of his steps. . On a 1-4, the overlord doesn't cast tripwire. 5-6 the overlord, Balor casts it. Certain other cards like tripwire are held until there needed, or when a overlord would play them.
Quick example of what I played tonight and how perfectly it worked. I ran the Fat Goblin quest part 2. Late in the game, I had 3 heroes, and the overlord (Balor) had Splig and 4 goblin archers left behind a closed door. On the overlords turn I thought of 2 scenarios that a overlord would do. A) Send the goblin archers through the door to attack the heroes. or B) Stack up in the hallway a few spaces back from the door and wait for the heroes to open it. (The heroes HAD to kill Splig for this quest so I had to get through that door). So on the overlords turn the "dark charm" card was drawn. That card lets you take control of a hero and move or attack with it). So I thought, what would the evil Balor do? And so dark charm was casted on Widow Tarha, she was moved right in front of the door, one of the goblins then opened it, and...it wasn't very pretty. 3 goblins unloaded and knocked her out, and the last one wound another hero for 3 wounds.
So bottom line, for me Descent isn't like playing chess solo. It's pretty solo friendly. If you think of a few well thought out moves a overlord (Balor) would do, let a D6 decide it, so there's that element of surprise and turn of events, it's a ton of fun. I REALLY have been loving descent, and have expansions on the way already. So if you jump in, make sure you grab a D&D Balor for your personal overlord. Have a good one