OSR is a fairly nebulous term, as it may cover different RPGs or years depending on who is using it.
For me, it covers D&D (and all the derivative clones) from 2E and before. It also covers Tunnels & Trolls, Avalon Hill and earlier Runequest, GDW Traveller, Chivalry & Sorcery, DragonQuest, Rolemaster / Spacemaster & MERP, Palladium Fantasy, Toon, 1st Edition Paranoia, WFRP 1e - the list goes on.
Were any of these games "tactical" in nature? I don't think so. Some where definitely rules heavy.
See, I know which games I consider to be covered under the umbrella of the nebulous "OSR", but I'm not sure what actually defines a game as being an "OSR game.
What defines an OSR style game to you?