1 Literally everything about New Super Mario Bros - Rayman Origins and Donkey Kong Country Returns
2 Final Fantasy VII's main storyline conflict of "girly-haired dude with massive sword versus another girly-haired dude with equally massive sword" - Xenoblade Chronicles
If you think Sephiroth's "one-winged angel" boss fight was amazing, then HOO boy, just wait until you see (spoiler) Zanza's
3 Chrono Trigger's overall gameplay, characters, music and especially storyline - Final Fantasy VI
4 Parappa The Rapper's music and gameplay in general, not to mention its main protagonist and especially its surreal-humor comedic value - Um Jammer Lammy and Gitaroo Man
Seriously, I wasn't kidding; once you've seen/played the likes of UJL, very few games besides Psychonauts, Earthworm Jim and Wario Ware even begin to compare as far as surreal humor is concerned
5 The 2D segments, giant battles, console gimmick usage and optional hard mode setting from Bowser's Inside Story - Mario & Luigi: Dream Team
6 The Legend Of Zelda: Ocarina Of Time's clichéd "Link huffed, puffed and blew Ganon down" storyline - Wind Waker and Twilight Princess
7 FNAF's usage of a psychotic robot teddy bear as one of its main villains - Danganronpa Series
8 Final Fantasy VI's evil clown antagonist, final boss battle quality notwithstanding - Batman: Arkham Asylum
Let's not talk about the Steroid Joker (shudders)
9 Undertale's cute but incredibly annoying obsession with god-awful puns and gratuitous leitmotif abuse - Mother 3
TRUE STORY: By the time you reach the Mecha-Drago boss battle in a first-time (or excruciatingly long-time-since-the-last-time) playthrough of Mother 3, there's a surprisingly good chance that you might actually end up losing the fight because Flint's incredibly stupid and useless tag-along sidekick Alec was so busy cracking horrendously unfunny jokes and complaining about his lower back pain that he completely forgot to remind Flint about his Toughen Up and Strengthen Up abilities for increasing his offense/defense stats back to normal when the boss lowers them, causing you to completely forget about said abilities altogether (the fact that Flint's portion of the game leading up to this boss is already so ridiculously easy even without using these abilities doesn't exactly help matters either)
10 Portal's sentient computer stalker of the main protagonist - System Shock and I Have No Mouth And I Must Scream
Danganronpa would also be a good counterexample for this
The Contenders
11 Undertale's "collect the seven mystical hearts" storyline - Super Paper Mario
12 Super Mario Maker's level editor - Little Big Planet 2 and Super Mario Bros X
13 Undertale's incredibly sad and disturbing final bosses - Earthbound and Mother 3
14 Resident Evil 4's horror elements, not counting the music - Original Resident Evil Trilogy
15 Undertale's first-person battle perspective - Earthbound and Mother 3
16 Dr. Mario's "match up the colors" gameplay formula - Bejeweled
17 Super Mario 64's level design - Super Mario Sunshine and Super Mario Galaxy
18 Metroid's soundtrack, especially as far as the Brinstar portion of it is concerned - Super Metroid
19 Metroid Prime's and Super Metroid's general themes of being alone and trapped in an alien world - Metroid Prime 2: Echoes
20 Literally everything about Kirby Super Star - Kirby's Return To Dreamland and Planet Robobot
21 The Legend Of Zelda: A Link To The Past's "dark world" cliché, I mean mechanic - Metroid Prime 2: Echoes
22 Playing as a wolf in The Legend Of Zelda: Twilight Princess - Okami
23 Literally everything about The Legend Of Zelda: A Link To The Past besides graphics and music - Link's Awakening and Oracle of Ages/Seasons
24 The overall humor in Mario & Luigi: Bowser's Inside Story - Mario & Luigi: Superstar Saga
25 Metroid Fusion's overall atmosphere and scare factor - Super Metroid