I love Holmes Basic. Aside from being my gateway drug (long story), it's just the perfect synthesis of old-school D&D and something simpler and more streamlined. As far as introductory sets go, it's stuffed with content; and the fact that it only takes its players to 3rd level evokes the wonder of low-level play and everyone's first time at the table. The spell inevitably fades with experience; but it begs the question: Is it possible to play Holmes Basic as a complete game? It's a question a fanatic like me loves to ask.
In fact, I asked it four years ago. It was a thought experiment written in the moment, but I've had time to refine the idea. Looking back, it needed the work. So here we go, once more tackling my pet project. If you own this excellent product, you can use the following rules to run Holmesian games in all their low-level glory. Just observe the following:
(1) Assume everything else is the same except for that which follows...
(2) Characters begin the game with maximum hit points at first level (i.e., 8 for fighting men and women, 4 for magic-users, etc.), rolling randomly for levels beyond first.
(6) Fighting men (and elves) add +1 to hit per level after first to reflect their prowess.
(7) Spellcasters get access to more magic and miracles, mainly to keep them relevant in a scaled-down game where higher levels will never be reached. Clerics get spells at first level, while magic-users employ more across the board per the following spell table: