So this is seemingly pretty hard O_o
(http://i.imgur.com/QMLoe.png)(http://i.imgur.com/ilqDy.png)
Okay, here goes.In order to participate in this competition, you had to find the Robo Fairy museum in Knytt Underground. There are a total of three different rooms in Chapter 3 that all lead to a hidden room connecting them for fast-travel purposes. But this room also contains the museum's hidden entrance. On its third floor, a bunch of cropped screenshots from Nifflas' games can be found. The competition required you to guess which games they're from.
Figuring this out took me several hours. Originally, I was fairly confident in most of them, but as it turns out, many of the screenshots are from particularly obscure parts of the games that sometimes have a nonstandard art style. But now I'm pretty sure I have them all figured out. I was able to locate all of the visual elements depicted in them in their respective games. I even found the exact locations of some of them.
#0: #Modarchive Story (Music Madness)
#1: Operator Status XH (The credits level)
#2: Within a Deep Forest (The minigame Hidden)
#3: Knytt (Evil-Ville's Secret Game)
#4: Knytt Stories (Waterfall Mountains in Gustav's Daughter)
#5: NightSky (Both versions of Level 1 in Slightly Nonsense) (This one was really evil. Both #1 and #6 closely resemble NightSky's normal art style, yet aren't from it. This screenshot looks nothing like most of the game, yet is indeed from it.)
#6: Saira (The pinball minigame)
#7: FiNCK (Area 5)
#8: The Great Work (The part with the tulips in the Dew Mines)
#9: Knytt Underground (The Black Hole secret in Chapter 1)
Note that I gave them the same numbers as their file names (which also happens to be the chronological order of their games, with exception of The Great Work).