Practical Formal Software Engineering is a textbook aimed at final year undergraduate and graduate students, emphasizing formal methods in writing robust code quickly. Engineering is an informal process using formal logics as tools and components to obtain timely practical solutions. This book takes an engineering approach to illuminate the creation and verification of large software systems in which theorems and axioms are intuited as the formalism materializes through practice. Where other textbooks discuss business practices through generic project management techniques or detailed rigid logic systems, this book examines the interaction between code in a physical machine and the logic applied in creating the software. These elements create an informal and rigorous study of logic, algebra, and geometry through software. Assuming prior experience with C, C++, or Java programming languages, chapters introduce UML, OCL, and Z from scratch. Based around a theme of the construction of a game engine, extensive worked examples motivate readers to learn the languages through the technical side of software science.