Burning fossil fuels is a big part of our heat production. Since this process is both non-renewable and polluting, finding other options is important. A clean and underutilized alternative is geothermal energy. However, it is often not considered due to sheer ignorance or misconceptions. HotPipe is a serious game designed to alleviate these problems, particularly among youth populations. Players control a drill to create geothermal wells solving a variety of puzzles, which introduce relevant cases for geothermal heating and show what geothermal wells are made of. The game focuses primarily on conveying the concepts of water circulation, relation between temperature and depth, androck type proprieties. From our game evaluation, players revealed a solid improvement on their geothermal energy knowledge.