Entering my top 10!
#17
Hint 1: World with altered physics.
Hint 2: Same franchise as #19 and #20.
Hint 3: This is also a 'sequel', but it's a lot more similar to the previous games than game #19 is to #20.
Hint 4: Games #20 and #19 are Pokémon Black & White and Pokémon Black & White 2.
Hint 5: Came out in 2009 (in 2008 in Japan).
#13
Hint 1: This game is pretty much just Dark Souls.
Hint 2: The game is set underground.
#12
Hint 1: 11th game in the franchise, and the first one that isn't numbered.
Hint 2: Instead, it's named after the system it's on.
#10
Hint 1: Yellow Helmet 2.
#9
Hint 1: Very recently got a new campaign.