TL;DR: Old school D&D in it's full glory, exactly the way its creator (Gygax) played. Sacrifice those two cups of Starbucks coffee and pick this bundle up, you are in for a great time!
This is a PDF copy of what's referred to as the "white box" or "3 brown booklets" or "OD&D", the game that kicked off the entire D&D craze back in 1974. Nothing has been altered, these booklets have everything you and your friends need to begin playing D&D the way Gygax played. Contrary to popular belief, Gygax didn't really use the Advanced D&D rules that much. In fact, the final campaign he ran for his players before his death in 2008 was using these 3 booklets. You'll find strange conventions here, such as Fighting Men (fighters), constant references to the Chainmail ruleset (not required), and the fact that every player class uses a d6 for hit points and all weapons/monsters deal a d6 for damage on a hit. As strange as all this sounds, the rules are very workable and allow for truly amazing games of dungeon delving and exploration. No feats, no rules-lawyers arguing about X rule, just you & your character against a very deadly and hostile dungeon that will eat you alive if you're not careful. Fun times, can't recommend this enough!!