The Euclid Flex font is quite expensive.
They used the Serif family of fonts. Small letters do not look good on the screen, the line height is very large. These fonts are appropriate in books. And the English version of the game uses a font family Sans Serif. These fonts are much better suited for screens and small letters.
There are several good free Cyrillic Sans Serif fonts: PT Sans, Fira Sans, Open Sans, Noto Sans. They can be downloaded from fonts.google.com and used for free in commercial projects.