I’ve updated my S&W White Box Essential Adventuring Rules with new wandering monster tables, the main change is that I added a table that tells you what wandering table to roll on, similar to how the process works in OD&D vol. III. So a party on the first dungeon level could end up with a wandering monster from the level one, two or even the level three table. I also added NPCs of various classes – so again more like OD&D (sadly without the level titles), and padded the tables so 1d12 is used at each level. There are a few new monsters, they come from Charlie Mason’s update to the Swords & Wizardry White Box rules. He incorporated the new tables into his latest edition, so you can get them free in PDF or near cost in print if you prefer.