As far the editions of Dungeons & Dragons go, the 1977 Holmes Basic started a very popular and well-selling sytem of the game. Intended as an introduction and stepping stone to Advanced D&D, it was the first basic set that essentially re-organized and clarified the original D&D booklets, albeit only to the first 3-4 experience levels. It was only 4 years later that the Moldvay Basic D&D came out, and it removed all references or intentions to lead to AD&D; it was its own game, and it stayed that way until the publication of the 3rd edition of Dungeons & Dragons by Wizards of the Coast after they acquired TSR and its games.
Blueholme Prentice Rules by Michael Thomas of Dreamscape Design is a retroclone of Holmes Basic, and it’s a darn good one. It has been recently revised with an incredible cover artwork by Jean-Francois Beaulieu. It may be my favorite RPG cover of all-time, no joke. The layout and design of this game is extremely clean and polished. The text is very easy to read as are the tables. The rest of the artwork is public domain, and while I usually don’t like that style these pieces fit perfectly.
Obviously if you’ve played any edition of Basic D&D and/or a retroclone styled on those rules you won’t find too much different in Blueholme. Race and class are split, but the restrictions for non-humans are there (I’ve always ignored these). In combat, Blueholme models Holmes D&D in that initiative isn’t rolled; order of combat is automatically determined by Dexterity scores (1d6 only rolled in cases of a tie). I used to not like this, but it is one less thing to worry about and makes combat go even that much quicker. Also, all weapons deal 1d6 damage; there is a optional rule for variant weapon speed and damage, and it’s something I would probably use. Large weapons can only be used every other round but deal 1d10 damage, medium weapons attack every round for 1d6 damage, and light weapons can be used twice in a round (during the attacker’s normal turn and at the end of the turn) for 1d4 damage. Like other Basic D&D editions and clones, there’s a nice compact offering of spells, monsters, and treasure.
While there are only 3 experience levels worth of play offered, the total material in Blueholme is more than enough for a group to get months and multiple adventures and campaigns out of it. If further levels of experience are desired, there are quite a few options available. You could grab the Cook/Marsh Expert D&D PDF, Barrataria Games’ Companion Expansion, or use another retroclone and adapt the rules and math from Blueholme you’d want to keep. Michael is working on the Blueholme Compleat Rules at a slowly-but-surely pace, and I for one will be patiently waiting to snag a copy of that! While Blueholme Prentice Rules reads great in PDF and is free in that format, I’d highly recommend ordering a saddle-stitched version from Lulu, it really is that much better. In fact, for a limited time you can get an autographed copy directly from Michael, but you gotta hurry while supplies last!