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.
Draco in Leather Pants: The Tasen in general, really. While there are a few good ones, they apparently contrast so much with the Komato that many, many fans make them out as almost saintly. While they aren't as vicious as the Komato, there's still the problem that they tried to wipe out life on Earth, and that's not touching on all their war crimes in the backstory - what they did to Iosa's planet stands out.
There's also a surprising amount of people who view Krotera as a Well-Intentioned Extremist doing whatever he needed to do to protect his people. You'd think that the game established well enough that he's a jingoistic tyrant with a 0% Approval Rating who chose to Alpha Strike Earth instead of making peace with the humans because he could.
Ansaksie can also be subject to this, although there's a bit of justification in that her more dickish actions are never mentioned in the game.
While it's rare, despite the fact that the game gives absolutely no reason to like him (and every reason not to), some players inexplicably love Asha, of all people.
Family Unfriendly Aesop: Some of the Komato state the logical, if abhorrent, conclusion that since their species is doomed anyways, the Tasen's desperate attempts to avoid their fate only lead to more suffering for all involved.
Krotera makes the exact same point with regard to humans.
Game Breaker: The Null Driver is a literal example. Firing it will lead to random changes in crucial data, up to and including changing the size and shape of the level geometry. Fortunately, the changes aren't permanent. Also a straight example as well. Proper use of it allows you to fully level up all attributes by Sector 2.
Which is why it's only unlocked once everything else is, and has to be reacquired every time you start the game.
It only lasts for thirty seconds, but Explosive Shotgun buff + Buster Gun (automatic shotgun) = Fully-Automatic, Unblockable, Instant-Hit Explosive Goodness.
Goddamned Bats: Komato Skysmashers, flying turret guns that dodge around so you can't easily hit them and pack some serious firepower. When they do go down they explode, which hurts you. To quote the game creator, "No-one likes the Skysmashers."
Memetic Badass: reallyjoel's Dad. After a Youtube user named "reallyjoel" posted a comment on Daniel Remar's own speedrun video saying that his dad could do better, there's been a running joke that reallyjoel's Dad is the best gamer in the world, and that there's a top-secret "reallyjoel's Dad" difficulty mode. Daniel said that reallyjoel's Dad played said difficulty and beat it so hard that it was wiped from existence. However, It's still in the game, and it's as impossible as they say.