$15 gets you an escape room in a box! It's a great deal, as long as you don't need the room part.
Unlock! is a type of one-shot game, serving up puzzles to the players in an approximation of the escape room experience. You're given a starting scenario and a handful of clues, which you need to inspect, use, and combine to access more areas and more clues, until you meet the ultimate goal (generally to escape from a place—they stick to the theme well). Everything is on cards, most of them with numbered backs; frequently your clues will require putting two cards together, which means adding them up and pulling the card with the sum of those two out of the deck. If you've solved the puzzle correctly, that card will move the experience forward. If not, usually it will be a penalty card that subtracts from the timer.
Oh yeah, this is timed, just like a regular escape room. (You can go beyond the timer if you want. There's no one to kick you out.) The game works through an app, which keeps track of time, lets you input codes, use machine cards, give clues, and so on. Unlike some games with apps, this one doesn't need much screen space; it's very effective on a phone. A tablet or laptop isn't necessary to really get the experience, a la Mansions of Madness.
As of this writing, there are twelve different varieties of Unlock! adventure, along with five demos. Only two of the demos appear to actually be available—one of which comes in the box after you buy it—but there's still one to download and print out if you want to see if this is your kind of thing. Beyond that, the twelve are grouped in four different "styles" of three adventures each, with a one, two, and three-lock difficulty box in each style.
Are they all good? No.
Are they all bad? No.
Is it easy to say which ones are good and bad, or is it a matter of taste? Now that is the question.
Some of this is definitely subjective. Sometimes, however, the design of a puzzle is objectively good (or bad) to a degree that it can be recommended (or not). The Wizard of Oz, although a max-difficulty puzzle and longer than most (ninety minutes versus the usual sixty), is very cleverly put together and designed with lots of pieces that work together very well. It's not for a group of players all new to Unlock! puzzles; it goes beyond the basic deck of cards, and requires a certain amount of creative thinking from experienced players that may simply not occur to those who haven't done these before. If you do have that group, though, it's fantastic. The only downside is that there are so many parts, it's easier in this one than most to flip an incorrect card but have it not be a penalty, which can either give you an undue advantage or just confuse the hell out of everything. That's not as big a deal as it may sound, though.
On the other hand, The Island of Dr. Goorse is supremely disappointing. It starts with a terrific concept—all players are split into two sides and have to solve their puzzles as smaller groups (or even individually, if you have fewer than four people) before they meet up and continue to the end as a whole. But, without spoilers, some of the puzzles en route are questionable in their design, and the final escape puzzle is intensely frustrating and poorly executed.
Of course, there will be people who disagree. Some people who pulled their hair out over the Wizard of Oz adventure will say I'm mad, as will those whose minds worked in just the right way as to solve the Island adventure without the hassles we encountered. Those people may even be right; I'm gauging these based on how I perceive their design, not how easy or difficult it was to solve the puzzles, but there could be aspects of these puzzles none of us saw that would make perfect sense if they were pointed out to us. Thus, although it's not especially gratifying, there aren't any specific adventures I can say you'll want to play or avoid and be almost completely sure you'll have a good time.
As a whole, though, the Unlock! series is well-designed, and the fact all the pieces survive (unlike Exit games, where there can be pieces which need to be torn up or otherwise destroyed to solve puzzles) means you can pass along or resell them when you're done. There's a lot of value here if you have a group of friends interested in this type of game; by all means, try the demo, but if you like escape rooms you'll probably have some fun here.
Score: Eight good escape adventures out of twelve (generically counted).