The best way to describe Vigil: The Longest Night is a hybrid, as it takes elements of the Soulsborne and Metroidvania genres and merges them together to create something of a rather unique game. At first, there might not be any Metroidvania mechanics at all, but the Soulsborne elements jump out at you. The Metroidvania doesn't reveal itself until a few hours into the game - as you have to reach a certain point before the first skill is revealed, the double jump. So how do you unlock double jump in Vigil: The Longest Night?
How to unlock the double jump?
Double jump becomes available after killing the second boss – The Brood Mother. During your journey, you will reach a small village in search of a girl named Bruna. Talking to the townspeople and Bruna's mother, you discover that Bruna has often entered a dark and creepy cave with someone called the Professor. As you progress, you'll discover this cave and venture inside, and it's filled to the brim with torture gear, bodies, and blood. Everything you face inside will be some kind of cosmic horror.
Eventually, at the bottom of the cave, near the end, you'll come across an elevator handle. When you have it, go up one floor to where the broken handle is and fix it. Climb all the way to the top and you'll find a decent pair of gloves - Percival's Gloves.
Keep going until you see a split path, a descending path, and an ascending path. The path leading up there is a door. This door is a shortcut to an owl statue, so be sure to go that way and save. To save you pain if you die and lose all cave progress.
The path down leads to a boss. After killing the hideous creature known as the Brood Mother, you will unlock the double jump ability!
See the boss early
You can actually see this boss early, but doing so will kill you, so don't do this without saving first! As you climb the path to the cave, you will see three people hanging around. You will notice that the lower floors are a place where you can pass. However, if you do, it's a massive drop, and it drops you into the boss room! You will die instantly, but not before seeing the grotesque silhouette of the boss.