This is a tool-assisted speedrun. For more information, see http://tasvideos.org/4123M.html. TAS originally published on 2020-03-05.
Heart of Darkness if a 1998 cinematic platformer action-adventure game developed by Amazing Studio and supervised by Eric Chahi, also known as the creator of Another World (AKA: Out of This World).
The game follows Andy as he is traveling through another world called the Darkland to rescue his dog, Whisky. Players progress through the game's linear storyline by navigating various environments and solving puzzles, all whilst attempting to keep Andy from being killed by evil shadows, hungry wildlife, and perilous obstacles.
Along with basic movement, such as running, jumping, and climbing, certain sections of the game give Andy additional abilities. The plasma cannon allows Andy to shoot lightning at shadows in order to disintegrate them. The Special Powers, which can also be used offensively against enemies, can additionally be used to grow and destroy trees born from seeds.