I'm gonna try again. Theres a game, I'm pretty sure I played it here,
you have to get to the key at the top of the screen, its not hidden. Theres very simple puzzle solving, the name of the level usually tells you how to complete it. Once you get the key, you unlock the door and go to the next level.
I cant remember what you play as, but its a keyboard only game. I seem to remember it being called X Levels (the x being the amount of levels, but I cant find any game with that title.) I'm trying to remember some of the levels, theres one that theres invisible walls, one you have to go through the border wall, theres one that you have to pause the game. The key is above a line that if you touch it, you fail. You have to get rid of it to get to the key. I just remembered theres a button you have to hit, and that gets rid of that line.