The main Osprey Rules seem to be fairly simple skirmish rules with some background and then a number of gangs/factions so you can start playing immediately.
I'm biased, so I'll bite my tongue, but I did want to say that we're not just focusing on skirmish games - in fact, not too long ago, I commissioned one for 2015 (sorry!) that most definitely cannot be called skirmish (more on that in due course). The apparent skirmish focus is more to do with the proposals that have come in than any specific policy!
As for the larger games (BOLT- or FOG-size), there's the big-battle ACW rules from John Hill coming this summer (
Across A Deadly Field).