So, I've been having a blast running short campaigns of this game and felt it was worth sharing with the community. While my players and I are newcomers to the OSR scene, we've found invaluable guidance in this particular book. It's packed with great advice on put together and run a rules-light, dungeon-crawling adventure. I personally appreciated the focus on being a fun playable game. If you're seeking a lighthearted 3-4 session break or aiming to introduce friends to an old school gaming experience, this book is an excellent starting point. It's easy to teach to your 5e friends and , if they are anything like my mine, they will love playing it.
The simple answer is entropy. It's much easier to poor a bunch of energy into something and have it express itself as heat than it is to retrieve spent energy out of an object. You can burn down a forest and make a lot of light and heat, but you can't spend light and heat to turn smoke into a dark, cold forest.