A certain enemy will die by suicide offscreen if the player character does not kill him in battle. Another enemy may die by suicide in the final cutscene; this is not shown in much detail but it is clear what happened.
The game has three endings, all of which can be seen as fairly bleak, but one of them is clearly the best possible outcome given where the game started. One of them is substantially bleaker, but the protagonist's main goal is still accomplished. The third ending is outright failure. The conditions for these endings make it very clear what is going to happen.
There is a lesbian couple in the game. It is possible for you to kill one of them in an early level. If you do, the other will die offscreen in a later level. These are the only confirmed LGBT characters in the game, but not the only identifiable characters who can or do die.
The invading aliens are carrying various futuristic sci-fi guns. The protagonist also has such a gun, but actually killing anyone with it is optional, and the story acknowledges the player's choices in this regard.
The game opens with an alien invasion. The player character's father appears in the opening cutscene and is stated afterward to have died in the attack. Other parents are never directly mentioned, but can generally be inferred to have died offscreen.
Depending on the player's actions, several named characters may die. A few antagonistic characters die no matter what the player does, though their manner of death may be affected by player choice.
An optional level transports the player character into a series of bizarre worlds. An item that can be found in this level allows the player to corrupt the game at will (these effects will vanish when the game is closed). A different optional item can be found that causes game text to change in random ways, but it can be disabled at any time and is not required to use.
The game opens with an alien invasion. The player character's father and sister appear in the opening cutscene and are stated afterward to have died in the attack. The player character's brother survives this attack, but may die during the game depending on the player's actions. Other family members are never directly mentioned, but can generally be inferred to have died offscreen.
A few tutorial comments refer directly to game controls and mechanics, though the characters treat this as in-universe text. There is an optional item which makes the game text sillier, occasionally by breaking the fourth wall. There is a hidden joke difficulty level in which the player character treats the game setting as "very hard video game" instead of interacting with it on a normal in-universe level.