Imagine if Arneson and Gygax were teleported from 1970 to the modern day, and shown all sorts of modern RPGs. Then teleport them back to 1970. Old School Hack is how they would have designed Dungeons & Dragons.
OSH is part of the Old School Renaissance, but rather than re-using the mechanics of early D&D, it provides modern approaches to the classic swords-and-elves experience, without turning it into a completely modern game. OSH feels retro.
For example, distance in combat is represented by arenas, a.k.a. blobs of terrain. An arena’s exact size or shape isn’t important; they simply represent relative proximity. So, players can easily use existing maps without wrestling a grid on top of it, while the map can still be subdivided into meaningful arenas.
OSH provides seven classes. If you pick one, you’re the only player this game with that class. This ensures that everyone has a unique role. You also get a character sheet representing just that class’s abilities and talents.
Talents are spell-like powers that can be used periodically, much like D&D 4th Edition’s powers. At first level, you choose one talent and may use it during the game. At each additional level, you choose an additional talent. Simple.
Speaking of leveling up: there are only 4 levels in Old School Hack. This strikes me as wise; the designer didn’t try to design beyond his experience or play-testing could reach.
Interestingly, turn order is determined by the type of action your character takes. Those choosing to hunker down in total defense go first, followed by ranged attacks, spells, movement, melee attacks, and physical grappling. This speeds up combat, to my surprise, because you deal with similar actions at once, leading to fewer context switches. It also gives combat a different feel. If two PCs both stand in the back firing arrows at the enemies, then they’re doing both at the same time both in-game and out-of-game. This adds a sense of camaraderie.
The game’s old-school aesthetic is greatly enhanced by its presentation. The PDF is full of sketchy pencil art. Not illustrations: titles and borders are “drawn in pencil.”
More importantly, the entire system combines to provide a play experience that’s simple to grasp with just enough tactical richness to make each fight unique.
You can download the full PDF for free.