Here is the full list of all 35 Necrolepsy achievements.
Beat the game on "Normal" difficulty.
Beat the game on "Hard" difficulty.
Beat the game on "Wake Me Up" difficulty.
Beat the game with "Always Nightmare" enabled.
Beat the game with "Die On Nightmare" enabled.
Beat the game with "Arcade Mode" enabled.
Get every single collectible on "Normal" or "Hard".
Get every single collectible in the game on "Wake Me Up".
Enable "Die on Nightmare" and "Always Nightmare" at the same time at the New Game screen.
100% complete all Necrolepsy difficulties and filters (Normal, Hard, Wake Me Up, Always Nightmare, Die on Nightmare, Arcade Mode) and get every achievement related to it (And I Can Get Back To Being A Young, Single Girl!; Those Who Hunt Items; If There's a Hole...; Fortify Intelligence).
Get over 100,000 points in "Arcade Mode".
Listen to Lira's dialog about skipping cutscenes without skipping it.
Trick a Mighty Roller into falling into a pit of spikes in Shanoa Sanctuary.
Kill a lich without disabling their pain reflection ability in Fortune Fortress.
Get 50 hits on the beach ball at Beardsley Beach in normal mode.
Get 50 hits on the beach ball at Beardsley Beach on nightmare mode.
Beat Normal's Boss Rush mode in under 9 minutes.
Beat Hard's Boss Rush mode in under 10 minutes.
Beat Wake Me Up's Boss Rush mode in under 11 minutes
Beat Boss Rush Mode on Normal difficulty!
Beat Boss Rush Mode on Hard difficulty!
Beat Boss Rush Mode on Wake Me Up difficulty!
Beat Boss Rush Mode on any difficulty with Arcade Mode enabled!
Beat Boss Rush Mode on any difficulty with Always Nightmare Mode enabled!
Parry drowning to death.
Parry a vampire and suck its blood instead.
Complete Milly Marathon on Normal difficulty.
Complete Milly Marathon on Hard difficulty.
Complete Milly Marathon on Wake Me Up difficulty.
Complete Milly Marathon on Normal difficulty in under 14 minutes.
Complete Milly Marathon on Hard difficulty in under 15 minutes.
Complete Milly Marathon on Wake Me Up difficulty in under 16 minutes.
Beat Milly Marathon with the Arcade Mode filter on.
Beat Milly Marathon with the Always Nightmare filter on.
Go to Milly Marathon's menu, but decide against playing it. Dangit! I worked hard on that mode too!