I'm currently using sound effects ripped from tetris.com, and as you can see it's not very graphically interesting. At some point I'd like to make my own sound effects and artwork - I might go for a "drawn on paper" aesthetic.
Another big thing I need to work on is having proper game menus, with settings, highscores etc.
Oh and I forgot to mention, this is all written in Python with pygame.
Got the main gameplay graphics pretty close to pixel-perfect.
The only problem is, I just found out that The Tetris Company is infamously litigious, so I'll definitely have to dial back the similarity if I ever want to publish this project...