Dark, atmospheric, awesome. Just ignore the plot.
Heart of Darkness
has to be one of my favorite games of all time, and this is in no small part due to its dark and genuinely creepy atmosphere. The game does an excellent job of conveying a deadly and hostile world that you'll have to navigate as player. Contributing to this is its complete lack of anything resembling a HUD, making the experience more immersive, and the fact that a single hit by anything
is enough to kill you. It's not just playing a game, it's fighting tooth and nail to survive.
Which is why the actual story is so baffling. A kid travels to another world with his homemade spaceship to save his dog? It sounds like the mother of all excuse plots, yet the game is full of cinematics, which were a novelty when this game was released, thus ensuring that the story would draw a maximum of attention to itself. And that story is dumb, dumb, dumb.
So my advice is to just ignore it and focus on surviving the fantastically creepy world the game designers came up with.