Simple, straightforward set of rules that I could grab half an hour before game time and use to resolve a search for a mysterious island. The rules for weather, and precipitation are very straightforward and the encounters are simple but offer plenty of examples to get the GM's creative juices flowing.

This is my favorite class/level game. Not a retroclone, but a very successful attempt to preserve the old-school feel while operating with more modern and flexible mechanics. The pie-piece approach to multiclassing is brilliant, and Luck Points answer all my complaints about hit points in old school D&D. The key dX mechanism models the shift from calm and professional to frantic and occasionally heroic. Read it for mechanical inspiration, play it for fun!

Not designed for the current (2nd edition) version of the game, which gets rid of the Priest. Not a ton of space for equipment if you make use of containers' ability to carry lots of not-quickly-accessible objects.

A solid, workmanlike look at 5e weapons, the gaps in the lineup, and duplications. The author adds a few weapons and discusses the various properties (including adding a new property). To my mind the book goes a little overboard in trying to differentiate weapons (example: giving the trident the new "trip" property to differentiate it from the spear) but that's a minor complaint. The biggest value I see is giving newer DMs an example of how to think about weapons systematically.

I bought it on sale for $1.99 and think it delivered good value for the money.

Creepy, evocative, and well-structured for table play. An actual adventure, not a railroad or a novella posing as an adventure. Minimal prep needed to run this brief-but-satisfying adventure.

This book has a lot of useful advice, but it's also espousing a philosophy that I think is poisonous to the game, and that's an attitude that prioritizes heroic fiction over player agency. From Chapter 24:

Tweaking combat is one way to change a beat from fear to hope, or vice versa. You can do so by adding monsters to make the fight harder, or removing monsters to make it easier. If the characters have been having an easy time of it, they might walk into a room full of armored ogres training and sparring. If they’ve been having a hard go of it, maybe they stumble across a lone ogre, face down and asleep in her plate of raw meat.

This is the sort of thing that saps player agency and devalues player skill. If they've been having an easy time of it, it's because they've been using lateral thinking and clever tactics to efficiently defeat obstacles. Why would you punish that by throwing extra obstacles at them? If they've been having a hard time of it because they tried to Leroy Jenkins their way through the dungeon, why would you reward that behavior by smoothing the path for them?

In fiction the hero always barely wins the last battle, bloodied and exhausted and depleted, because that's all scripted and the author is the only one with agency. Trying to recreate that in a role-playing game sacrifices all the strengths and freedom of RPGs to turn them into a mediocre imitation of a book or movie.

There are a lot of good suggestions here-- I'd encourage anyone to read chapters 8, 15, 21, and 22. Just tear chapter 24 out of your copy of the book entirely and forget it ever existed, and the remaining chapters comprise a 4-star resource.

I'm going to begin by echoing Raj B. here: I'm roughly 70 pages into this 300+-page PDF and I'm so sick of the phrase "see Barrowmaze Complete" that I could scream. Even an entry in the back that says something like "Funeral Pyre Zombies -- see Barrowskin Complete or reskin Fire Snake from MMp265" would be an improvement. This was sold as a standalone product, not as a Barrowmaze supplement.

The maps are great, there are some good ideas (if not as fleshed out as I'd like), the writing is mostly clear. I'd like to see this designed better for use at the table-- inline stat blocks would be handy to avoid flipping back and forth and back and forth. Also, there's a tendency to give information a little late. Room 42 of one area says "A detachment of [enemies] normally guard this chamber (85%). If not, they may be training in #27-28." Think that might be worth mentioning a little earlier, say in #27 or #28? Me too.

If you're planning to buy one Greg Gillespie megadungeon, don't get this one. Buy Barrowmaze instead. It's not perfect, but it's good, much better than this.

If the publisher were to go through and make the other monster stats available as a free PDF or something, I'd probably rate this as 4 stars. As it is, I'll steal a few ideas/mechanics from this but I have no desire to run it for my players. When I'm paying $30ish for an adventure module, I expect that I'm paying for someone else to have done most of the work for me. That wasn't the case here.