I wrote this years ago before I learned about a lot of programming theory and design — as such, the codebase is very much a tangled mess as I was oblivious to the advanced concepts of object oriented programming, functional programming and test-driven development. You're free to play around with it, but I would personally recommend against anything beyond toying with the project as there are anti-patterns and design issues everywhere that require so much work to solve, you're better off creating a project from scratch.
That said, I have moved on to bigger and better things, such as assiting the development of TETR.IO and an upcoming game lead by the organization Tetra Dev Studio. I may randomly toy with this project, but please don't expect anything.