TSA writes: The modern Ninja Gaiden series featured what were widely regarded to be some of the most difficult series around upon their original release. Of course, when first game came out for Xbox in 2004 and its enhanced Sigma edition for PS3 in 2007, the series predates and overlaps the earliest games in the Soulslike genre. The games found in Ninja Gaiden Master Collection have got a very different interpretation of high difficulty.
Source: N4G PC Ninja Gaiden Master Collection Review (TheSixthAxis)