So he spent 10 years making a pseudo-3D version of Sokoban with 2010 era graphics?
I think he must have spent 9 years working on his new programming language and one year working on the game.
If you want to do X, "build a programming language first then use it to do X" is a tried and true way to never do X.
If you want to do X, "build a programming language first then use it to do X" is a tried and true way to never do X.