And it's also one of the most impressive displays of RenPy's capabilities you'll ever see.
Plenty of games do amazing things with ren'py that you wouldn't think were possible just by looking at the dialogue DSL. Maps, HUDs, minigames, incredibly dynamic pathways through the game. But DDLC takes it to a different level, partly by looking so "normal" on its surface.
In college I made some spare cash writing Ren'py games for some creatives online who had the writing and illustration chops, but needed programming help. At the time, DDLC was the model for great game design in Ren'Py. There are plenty of more technically impressive Ren'py games nowadays, but DDLC is still a terrific example of technical sophistication facilitating the story.
Ren'py is awesome by the way. A tour de force of software design, in my opinion.
Isn't RenPy basically a game engine under the hood? So if you have the programming chops, you can make anything with Python.
I've played it, but what's impressive about this game (technically)? I don't remember its implementation being anything special as opposed its plot.