I finally understood what to do lol.
So first you only have the grab ability. Grab an enemy to aquire its power. The boxer gives you the boxing ability. With that you can smash crates. You first have to select the ability in the menu though. Then you can go to the ninja in the bottom right corner of the map and get a sword. With the sword you can cut bushes. From there its more of the same: explore, grab abilities, repeat.
The blue chests contain additional hearts for which you have to buy keys for 20 wood.
Ok game but needed more guidance imo.

Absolutely loved this, despite a few issues (i.e: getting stuck for moving too fast, bow not being the most... accurate thing in the world, as seen on my video) it's still a really good game and I enjoyed playing it a ton. My Girlfriend actually suggested this to me and I am so happy, this brings me some nostalgia because of... The Final Boss... Anyway, amazing game, loved it, really good work <3

This is a fairly decent game graphics wise, the music made me turn my sound down. Yes i was one of those who were confused as to the menu system (press space to access and SPACE (not EXIT) to go back to game. but i got a key after trading some wood, found a second cave that led to a different area but after all my exploring i couldn't seem to figure out where to go or how to get past the little bushes that were blocking all the paths and the rocks in the original tunnel stumped me too. Any help would be appreciated.

If your still confused on the second screen, open the menu with SPACE and then move your mouse on the punch ability after killing the first enemy, then press Z as your mouse is under it to acquire it.

Some people had trouble with the menu, press SPACE to open and close.