Hi, thank you so very much for trying our game. Yeah, our game has some design flaws... to enter the first door you have to "Equip" the difficulty you picked then press up in front of the door. We should have made a select screen for the difficulty, instead, For the solo challenges, it's probably not clear enough, it's about the medals, kill your enemy once, you get bronze, twice, you get silver, gold and diamond. You have different kind of challenge too on the far right of the stage selection. It's really helpfull for us to see someone else playing it, thanks again for your video!