This game is running in the console. The technology used is C++ (good language for optimization).
That type of game it's good for learning C++ the right way, also a good deep dive into game development.
Open a console in the same directory as the main.cpp file is.
Run the following commands:
>>> chcp 65001 This will allow the console to display Unicode symbols
>>> g++ main.cpp This will build the code written in "main.cpp" file
>>> ./a.exe This will run the .exe file