The whole series (except the smitemaster's collections) was cheap on the Summer Sale and happened to fit into the budget I'd set aside for it. I'm starting with the latest game in the series, Gunthro and the Epic Blunder, because it's supposed to be the easiest one, and it's also a prequel.
DROD is a somewhat unknown but long-running puzzle game series that's kind of like Chip's Challenge with a sword. Move in one of 8 directions on your turn, or choose to rotate your sword clockwise or counter-clockwise. Rooms are cleared when all the monsters are killed. There are many different types of monsters who all have different movement patterns. So far none of the puzzles have felt as rigid as Sokoban where there's exactly One Solution that you might have messed up 25 moves ago and didn't find out until it was too late. Of course this is the easiest game in the series, supposedly, so maybe that changes later on, but I did play a good portion of the demo for the first game and that also never happened.
The audio is good. I've been impressed with the soundtrack the whole time. Also there's voice acting in it. It's extremely good and by that I mean some characters sound fine(like Gunthro here) while others are recording with an apparent cheap mic in an echo-y room. I mean this with all sincerity: it's incredible and I hope they never change it.
DROD is on Steam or you can get it directly from the developer's website, which also has demos for each game.
Here are a few tricky challenges I've done and managed to record video of thanks to Steam's new not-Shadowplay feature.