Penny Arcade's debut game is the best thing to happen to episodic adventure games since... Ever.
A lot, actually. The most important aspect of a traditional adventure game is its story, and Penny Arcade Adventures is certainly not lacking in this area. The story begins with your self-created protaganist simply minding his own business, raking the leaves on his front yard, when a giant "Fruit Fornicator" robot comes by and stomps his house into Oblivion. From there, Comic-Book like 2D cutscenes guide your character into a journey with the web-comics main characters, Gabe and Tycho, along an escalatingly intense story that delves into much darker and more mysterious matters than just a simple revenge quest.
The story of the game is littered with bouts of Penny-Arcade's famous humor. It has flat out puns complete with character driven punchlines as well as gags hidden within environment objects that you could miss. There are also several moments of genuinely well-written serious dialogue, as well as several moments of "Oh snap, that was awesome!" moments in the storyline. Fans of the series' humor will no doubt enjoy the game's storyline and humor, while those who don't will probably still be entertained by the dynamicly unfolding tale.
Like many other modern adventure games, Penny Arcade Adventures has a very simplistic but generally appealing artstyle. Characters and environments in the game are good 3 dimensional translations of their 2D counterparts in the cutscenes, and everything is given a general cartoonish appearance. The game also looks fairly good on a technical level, with an overall smooth appearance and almost no framerate issues. In all, the game has a very good visual style about it.
The part where Penny Arcade Adventures differentiates itself from most traditional adventure games is its combat. Precipice uses a pseudo-realtime queue based attack/combat system. Each battle starts with a "Roll for Initiative", with the character/enemy who gets the highest number getting to start the battle first. Each character or enemy has multiple attacks, which must be fueled up by waiting differing periods of time before activation. Inventory items are also used in real-time, just as attacks are. Special attacks are often driven by well-timed button combos. The combat system results in a good combination of turn-based tactics with real-time frantic action. The end result is a very enjoyable and sometimes difficult combat system which ends up being one of the main sources of entertainment in the game.
Overall, Penny Arcade Adventures: On the Rain-Slick Precipice of Darkness adds up to be the start of another enjoyable episodic adventure game, whicch also brings something new to the table in the form of a well-implemented combat system. It is recommendable to just about anybody, from series fans and RPG veterans to general humor lovers and casual gamers. It's only seven hours long, but Precipice is seven hours of some of the most enjoyable entertainment you'll ever find, and this is a series that adventure fans will definetly have to keep their eyes on.