Internet of things has been one of the predominant research areas for the past two decades. Many application domains have embraced it to solve challenges that have long been considered hurdles. A recent trend in information communication technologies is integrating miniature sensing devices to elevate the experience in serious games. Serious games are games whose sole aim is not entertainment but rather to serve as a source of information and learning in a playful manner. Serious games are becoming one of the sizzling literature topics and are applied to every part of human lives, such as education, healthcare, and physical training, to name a few. Internet of Things, the biggest provider of modern-day games via personal mobiles, can be utilized to design serious games. However, deploying serious games in the Internet of Things environment engenders new challenges. This paper aims to provide a comprehensive survey on Internet of things-enabled serious games and investigate the challenges towards their realization. First, we highlight serious game domains and spot the evolution and motivation that lead to Internet-of-Things-enabled Serious Games. Later, we classify the state-of-the-art by devising a comprehensive taxonomy. In the end, we present numerous unaddressed open challenges in the current form of the state-of-the-art and identify future directions.