The idea is to remain rules-agnostic, even though a certain number of rule sets are put forward on this blog, namely: Lamentations of the Flame Princess (LotFP), Renaissance, Monsters & Magic (M&M) or 13th Age. Please refer to the sidebar for the relevant links.
LotFP, whose default setting is Central Europe during the Thirty Years' War (1618-1648) is the most obvious candidate because it shares the same geographical location as Lamentations of the Blood Countess (Central Europe), and almost the same time-frame — I tend towards the turn of the 17th century myself.
Well, if you'd rather you'd be playing brave Englishmen, I direct you to Jeremy Duncan's O Brave New World, a free PDF supplement to LotFP. The premise is as follows:
The year is 1589. PCs are English sailors, soldiers, gentlemen, and their hangers-on. A sudden TEMPEST struck whilst engaged with the galleon La Visitación de Nuestra Señora, and all hands lost beneath the waves. By the grace of GOD, you awake to find yourself and several comrades washed safely ashore on an unfamiliar beach.