Being the guy who wrote Unbelievably Simple Roleplaying, you can probably tell that I'm a fan of simple, minimalist rules. Swords and Wizardry White box is my favourite version of D&D because it's simply the boiled down essence of what that game is. Now The Black Hack has arrived with much fanfare and whooping, presenting a new era of micro rules for OD&D. Oh, and it's super.
Erupting from the British OSR scene, The Black Hack is both a 'hack' in the more traditional sense and a ruleset in its own right. It ain't hand holding new players into what role-playing games are - it assumes the audience is already familiar with the game, which is a fair one to make. I can't see to many new GMs picking out The Black Hack as the first game they run.
That said, the main rules have everything you need: classes, weapons, monsters, spells and more. All within its slight 20 pages - quite a feat. But like Salt & Shake crisps, Black Hack sacrifices some flavour for DIY goodness. Flipping to the bestiary you will find pages chock full of monsters, all slotted into single line stat blocks. It's distilled D&D - you're not getting any evocative descriptions - it's cut and dry. This brings me back to the point that this should probably be used in conjunction with another game, like S&W.
Mechanically, there are several adjustments to what you might already be used to. AC has been replaced by reductive armour, the way Tunnels & Trolls works. Other mechanics have been nabbed from 5e of all places. You've got advantage and disadvantage, allowing you to roll again on an adventure and vice versa for disadvantage. Dedicated saves have been chucked out of the window - instead you roll a save on an attribute like dexterity or strength. It's beautifully elegant. As is the fact that everything is roll under. Want to climb a cliff? Roll under strength. Want to shoot a guy with a bow? Roll under dexterity. Oh yeah, enemies don't roll to attack, which could have been an inspiration drawn from Dungeon World or the Cypher System. Instead, the player rolls under a given stat. Miss the roll and take damage, which is dished out in d8s. This may tick some GMs off, but personally I like it. It feels like it lifts a burden off the DM. Your experience may differ.
We've not yet touched classes, of which there are four. No races - just your typical fighter, wizard, thief and cleric, although with some name swaps. Each class has its own hit dice and set abilities, with one class per page taking up minimal space.
It seems fairly easy to convert an existing OSR adventure for use with The Black Hack, so your current modules won't go to waste. The only real issue I have is that it seems to be set out all over the place, with no clear logical layout. It's not a biggie, but it was something that stood out.
So should you get The Black Hack? I'd say so. If you're an S&W fan then this is a great little ruleset that lives by the code 'no muss, no fuss'. If crunch is your thing you may still get something out of it, but it's doubtful. It's an inexpensive book with great mechanics and already quite a bit of community support.