Serious games (SGs) about Chemistry have the potential to cope with challenges, such as students' low performance and lack of motivation for the subject. However, the majority of existing SGs for Chemistry have the form of educational applications infused with some elements of entertaining games. The aim of the study presented was to design and evaluate a new SG with rich game mechanics for Chemistry. The game is called Elementium and revolves around basic topics of Chemistry, such as chemical elements and compound terminology, creation and everyday usage of such elements. The main goal of the game is to familiarize junior high school students with the aforementioned subjects. The design of Elementium was carried out implementing the dimensions described in the Four-Dimensional framework, as proposed by de Freitas and Jarvis in 2006. After the development process, Elementium was evaluated by people in the field of education that are currently teaching or have taught Chemistry in the past. The participants play-tested the game at leisure in their homes and evaluated it based on the key criteria for SGs design proposed by Sanchez in 2011, as well as other quality indicators established in the literature. Elementium was positively evaluated by Chemistry teachers in terms of its acceptance, usability, didactic utility, and game environment. The positive results concluded from this evaluation show that Elementium is fulfilling its main purpose and can be used as a supplementary tool in the teaching process. However, its true didactical effectiveness has to be confirmed through a study with high school students.