Monomoon

Here is an excerpt from Monomoon's Steam description:

With no proper instructions, you must deduce and achieve your goals as you solve puzzles, find mysterious items, and uncover secrets hiding right under your nose.

Features

• Explore a small open world "Metroidbrania" that you can (probably) complete in a few hours, or dig deeper to find all that's hidden within.
• Layers of secrets, ranging from simple puzzles to cryptic mysteries and hidden game mechanics.
• A mix of platformer and point and click control schemes, utilizing both the keyboard and mouse. (Controllers are also supported)
• Nonlinear exploration and progression - explore and discover things at your own pace.