Crypts and Things is an OSR game from D101 Games, written by Newt Newport. It's an OSR game as opposed to a retroclone, because it's not designed to mimic an older form D&D exactly, but uses rules tweaked to fit its setting. In this case, swords and sorcery in the vein of Robert Howard (Conan), Clark Ashton Smith, and Fritz Leiber (Grey Mouser and Fafhrd).
There are four classes — the barbarian, the fighter, the magician, and the thief. The barbarian is pretty much a fighter, with a few special abilities, and owes more to the class originally appearing in White Dwarf #4 than the later, Dragon/Unearthed Arcana one, though it does retain the infamous "barbarian horde" at high levels.
On the other hand, the fighter isn't simply the standard OSR fighter. He can learn a number of fighting styles, which give them a small bonus to something. For instance, +1 to hit, or an extra +1 when using a shield, or a slightly improved armor bonus when only wearing leather armor. These bonuses are rather small when compared to traditional D&D, they are consistent with this game, which has few magic items.
Magicians are handled somewhat similar to the old Lankhmar setting for AD&D. There is no clerical magic, but many of their spells are considered "white magic", and thus castable by a magician, with most of the traditional magic-user/wizard spells being "black magic" or "grey magic". Magicians do not have to pick what kind of spells they can cast (unlike the Lankhmar setting rules), but there are consequences to casting anything but white magic spells. Grey magic spells cause damage to the caster, equal to twice the level of the spell cast (so a 4th level grey magic spell would do 8 damage).
Black magic has a graver cost. Simply memorizing the spell in the first place requires a blood sacrifice - either it does damage to the magician (not just hit points, constitution) or requires killing a sentient creature. It also can take a toll on the caster's sanity, each spell cast requires a saving throw or face a loss of sanity (essentially losing wisdom points).
The thief is a class that often, well, stinks in OSR games. Usually they fight terribly, have bad saving throws, and have low hit points. Here though, the thief is quite viable. They don't fight as well as fighters (or barbarians) but can hold their own. They get a good number of hit points, 1d6+1 per level. And their saving throws are actually the best.
At first glance, one feature of the thief is missing - the ability to backstab. That's because every class in the game has the ability to backstab.
Combat pretty much follows along old school D&D lines. Roll a d20, compare it to the armor class of the target to see if it's a hit, and then roll damage if it's a hit. Both ascending and descending types of armor class are supported, though ascending could have been handled a little better by simply having an attack bonus column on the character charts, rather than having one big combined and confusing chart.
The big difference from the average OSR game is that it essentially uses the wound point/vitality point system used in Star Wars d20 and Spycraft, albeit just using the constitution score instead of a separate total. Basically once player characters run out of hit points, they start taking damage to their constitution. This concept is actually quite old school, much like the barbarian class this uses, this idea was originally in an old issue of White Dwarf.
This solves a lot of problems of D&D, especially low level D&D. First level characters are still somewhat fragile, but not likely to die in one blow. Magical healing is similarly not as needed, since hit points are regained quickly (while constitution points take a while).
Skills are based on saving throws. There is but a single saving throw (this game being based on Swords & Wizardry), so classes get a +3 bonus on class skills. On the flip side, all classes can attempt all skills. So for instance, a 2nd level Thief has a saving throw of 13, as does a 2nd level barbarian. Both would need to roll a 10 if they used their climbing skill, since it's a class skill for both classes (and thus get a +3 bonus), but if the barbarian tried to open a lock, he would have to roll a 13 or better, while the thief (which has open locks as a class skill) would only need a 10.
As mentioned, spells are not divied up along the usual class lines, as there's only one spell casting class, the magician. Instead, most of the standard D&D spells are categorized as white, black, and grey magic, depending on the nature of the spell. Healing spells are white, damage and necromantic spells are black. Grey is a mix of creation and offensive, but not damaging spells, like sleep and hold person.
Although the class tables go up to 21st level, spell level stops at 6th. So things don't get too outlandish. There is also no raise dead.
You are given a sketch of a setting called Zarth. It's perhaps the weakest part of the book, being a bit on the generic side when it comes to names and descriptions. Ash Plain, Cold Lake, Drowned City, Ice Coast, Isle of Skulls are probably names that could exist (I personally live atop of Windy Hill) but are kind of dull.
It's really just a list of names and a sentence or two. You do get a pretty nice map, though.
Close to 50 pages of the book are devoted to monsters and opponents. These are all sword & sorcery style creatures, usually horrible monstrosities. Some are standard D&D monsters, but many are new.
The stat format is standard enough, but each entry starts off with a short piece of fiction, much like the monster entries in Call of Cthulhu. Despite this, you still get 2-3 monsters a page, so there are a good number of them.
Lastly (at least until the Appendices) is a short sample adventure, the Halls of Nizar Thune. It's a short, 4 page dungeon (or rather "Crypt") crawl with 22 keyed areas. As far as starter adventures go, it's a little dull and not particularly rewarding when it comes to loot, seemingly somewhat at odds with the GM advice section.
It's not exactly an attractive book. The layout is purely functional, and there isn't much art. But it's easy to read.
I really don't like Swords & Wizardry for a variety of reasons, so wasn't expecting too much out of this. But Crypts & Things addresses many of my complaints of that system, and in some cases, of D&D. On the other hand, it also highlights one of the things I don't like about S&W, the single saving throw. Since the saving throw is used so much in this, for skills as well as saves, it's a bit repetitive with using the same number constantly and for everything, no matter the situation. Blood & Treasure also uses saving throws as the basis of skills, but has three of them (like in d20/3.x) so it's not always the same roll.
The obvious comparison is to Astonishing Swordsmen & Sorcerers of Hyperborea, a game meant to also cover the swords & sorcery genre, and claims much of the same inspiration (Clark Ashton Smith, Moorcock, Robert Howard). While I like AS&SH a lot, this captures the spirit of those inspirations much better, at least in terms of rules, as AS&SH sticks very close to AD&D 1e. It's also perhaps the best rules light incarnation of the OSR rules, exceedingly simple to play.