Oh sorry for late response! "R" is the reload button. If this isn't the issue with the gun then there is some sort of glitch we will have to look at, so let us know! Unfortunately, due to the unfinished state of the project, the only way to know how to progress in some places is through the video tutorial. In short, once you unlock the jetpack, you gain access to the other floors via the abandoned elevator shaft in the center of the world. This allows you to exit the tutorial area and complete the rest of the game. Sorry for the inconvenience and I am really happy you enjoyed our game!