These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: I Wanna Be The Guy
Big In Japan: This game is much more popular in Japan than in its home country of the United States. In fact, there are several Japan-made fangames, such as I Wanna Be the Love Trap. Videos of this game are popular on Nico Nico Douga, the Japanese counterpart to YouTube, and get much more views there than on YouTube. Also, many Japanese players have recorded themselves playing the game on Impossible (no verified full clear run has been made without autofire, however, with the exception of two which are both hosted on YouTube).
Crosses the Line Twice: The game is so insanely over-the-top difficult that you will change your reaction to dying repeatedly in the same spot from annoyance to cursing to laughing. It's the only way to handle a game like this.*
Of course, some people head back to cursing again after a while. It can get a little, lets say, messy.
Goddamned Bats: Most of the enemies. Strangely enough, the bats are probably the only things in the game that actually don't kill you upon touch.
Good Bad Bugs: Some bugs that benefit the player were actually kept in the game.
What may very well be the most game-breaking "bug" is the fake save point on Impossible. Killing it makes a perfectly usable save point appear for exactly one frame on the screen. Killing it while having a bullet EXACTLY where the save point would appear allows you to save the game.
Some bugs allow so much sequence breaking that people have completed the entire game in 18 minutes.
In the Tetris room, it's actually possible to jump through some of the pieces. However, the jumps are quite difficult to time, so it's not really that useful.
Memetic Muta—*SPLAT* GAME OVER - PRESS 'R' TO TRY AGAIN
That One Boss: While technically every boss fits this category, Dracula easily takes the cake as one of the hardest bosses.
