He also decided to wield this new language that is God’s gift to game programming to build… a block-pushing game?

That's the confusing thing to me. At least with a game like Factorio they made their own engine because they had to simulate thousands of machines and millions of items moving around each tick. But a sokoban-type game with cartoony graphics, that would be fine on off-the-shelf Unity or even something like Godot. Like, I've played HTML5 games with more demanding graphics.

A very good and large Sokoban game though. I've been playing it since release and still only at 460 puzzles. The counter goes up to 920 as far as I know.

It's also very well designed in my opinion. Love the way the ideas are introduced and built on top of each other.