Index Card RPG

Essential Game
This is the 2nd edition of of the Index Card RPG Core book (ICRPG) by Brandish Gilhelm aka Hankerin' Ferinale. The author has run a video blog on Youtube for years and can be found by searching for Runehammer. He is a high energy, insightful and creative guy with a lot of gifts to share. ICRPG feels exactly like that...a gift for us gamers.
The 2e core book itself is 200+ pages of reductionist role-playing game design. Mr. Gilhelm started out some years ago with 5e and a desire to reduce it to its core in an attempt to "hot rod" the game something like car enthusiasts who hot rod a stock built automobile to make it faster, more exciting and distinctive looking. I think he has done a great job, although at this point, I think the game's name could be re-tooled.
ICRPG started out replacing terrain and physical combat displays with art drawn on index cards, hence the name. Over time and play development, the index card gimmic kinda took a back seat to the game mechanics in my opinion. What we have in the 2e core book is a lean, mean RPG system that is original and creative and re frames how I look at the games I play with other systems.
ICRPG mechanics center on just a handful of concepts: Turn, Target, Attempt, Effort, Loot and Stats.
The game is always played in turns. The referee starts each turn with asking a player what they want to do and then proceeds around the table asking each player in turn what they want their PC to do. If dice are called for the player makes an Attempt by rolling a d20 and trying to beat the Target number for the encounter/room/ what-ever. Some tasks such as killing a foe, deciphering an ancient tome or tracking prey may require Effort be rolled for over several turns to eventually accomplish the task. Success leads to Loot which adds to the PCs ability. Stats are numbers that add to Attempt rolls and are also descriptive of the PC's abilities. Strength, Dexterity, Constitution, Intelligence, Wisdom, Charisma are the character's Stats. Armor makes it harder for enemies to hit you and is purchased like by the point like your Stats.
Turns can represent a variable length of time, such as Moments in combat, or Hours when not in combat or even Days when traveling or spending downtime. The point in ICRPG is each player states their Attempts for each Turn, that way everyone is always engaged in the game.
Each encounter, room, challenge or situation the referee presents has a Target number associated with it.  All Attempts made during that encounter/situation use the same Target number. Everyone at the table knows what their odds are of success and informed risk taking is thereby facilitated.
Some tasks are accomplished with a single successful Attempt, others take Effort which is represented by rolling an Effort die and accumulating Effort points until 10 is reached whereby a Heart is achieved. ICRPG uses Hearts to measure how tough something is. Creatures have one or more Heart. A puzzle can have a number of Hearts. A mystery can require Effort scores to equal one or more Hearts to be solved.
Loot (fun and story, of course) is what the game is all about. In ICRPG advancement is about acquiring Loot. Your gear makes you better at doing stuff and the accumulation of Loot is the reward for success and allows your PC to take on bigger and badder challenges. You don't really level-up in ICRPG, instead you accumulate Loot.
There is a lot more to ICRPG 2e, but that is the basics. It is a class based system with magic and technology that can support play on many different world settings. Two are detailed in the core rules book. Alfheim is the author's basic fantasy realm and its races, classes, magic and critters are described in enough detail to get the referee started on their own version of Alfheim. Warp Shell is the author's basic space opera setting and includes totally different races, classes and high-technology vehicles and gizmos.
Mr. Gilhelm has some excellent observations and advice to share on a number of game topics including painting miniatures, making tabletop terrain and running adventure games of all types and his videos are among the best I have seen in this hobby. Mr. Gilhelm knows his stuff. His Game Mastery section includes more than an average helping of good advice and makes this book really deserve the "Essential" tag I give it. If I were to teach a course on tabletop RPGs this is the text I would assign for discussion.
The core book is illustrated throughout by the author who has a very engaging pen & ink style. The illustrations are B&W with occasional red details and I find the style works perfect for the index card terrain and minis that are available as print and play digital files. If you are interested in what the World's Most Popular Game might look like as seen through a philosophical reductionist's eye so as to be just the bare essentials of game play only, ICRPG seems to be just that. Personally, I am intrigued and I can't wait to get it to the table.