Just had a fun evening playing solo using these sheets and White Box (just downloaded that to use for this). What a fantastic time, the tables work really well and the cycle runs along nice and smoothly. A fantastic piece of work! Just about to enter my first dungeon.
So, White Box (fantastic medieval adventure game) is a cleaned up and streamlined version of Original D&D. You can get the pdf free, or printed book on amazon for $5. many people like it cause it plays very simply.
The 3 stats comment has more to do with adapting the sheets to something like bastards. or Cairn, other simple variations on adventure games!