The trouble with defining the OSR is that it's not one thing but three! In fact, that's what gives it such power.
Behold, the trinity...
- OSR is a sign or badge of compatibility with early D&D. From a marketing standpoint, products labeled OSR should be more or less usable with original/basic D&D, AD&D, 2nd edition, 5th, and possibly even 3rd and 4th if one doesn't mind a little conversion work, scaling things back, etc.
- OSR is a style of play that lends itself to guidelines not scripture, DIY, non-standardization, wild-eyed anything goes creativity, freewheeling spur-of-the-moment improvisation (I'll give it a 1 in 6 chance of happening), and player-character determined campaigns, while avoiding character optimization, rules bloat, and roll play vs. roleplay. Additionally, death can come at any time. While GMs shouldn't be "gunning" for PCs, save or die is not uncommon.
- OSR is an aesthetic. The movement sprang from nostalgia of the 1970's and 80's: art, literature, sex, themes, attitudes, adventures, worlds... everything from an earlier period of tabletop gaming (when many of us were in or near adolescence). That which is considered classic, vintage, retro, and old school is sometimes called OSR even though it bears little resemblance to D&D. The Call of Cthulhu RPG, for example.
So, it's little wonder that confusion crops up when someone talks about his version of OSR and that particular definition is at odds with another's conception. Presumably, the more a thing (book, illustration, game mechanic, etc.) conforms to the aspects above, the more OSR it's believed to be. Yet, that doesn't mean lesser OSR things (relatively speaking) are not OSR or part of the OSR movement, just that a smaller consensus of appreciation exists.
As always, feel free to agree, disagree, throw a brick through my virtual window, etc. Comment, please! I want to know what you think.
p.s. Yes, I'm still trying to successfully fund my Revelry in Torth kickstarter. Every little bit helps. Thanks!