With the rise of popularity of video games, their localisation has also become a highly discussed question. However, from the academic point of view, certain countries are falling behind colleagues in terms of number of conducted studies, including Russia. The present dissertation aims to contribute to research on the topic of Russian video game localisation, in particular, linguistic versions made by fan communities. Using quantitative analysis of a case study of the indie video game Undertale, the dissertation analyses the quality of fan localisation of in-game text design using the QT21 Translation Quality Assessment (TQA) metric on a monolingual corpus of screenshots. The results show that the fan localisers were able to produce a high-quality Russian version of the video game in terms of in-game text design, making certain mistakes which can be corrected after conducting proper linguistic quality assurance.