The diegetic menu is a great idea. PLAY / CREDITS / EXIT printed on the drawers of a 3D server rack with little lights next to each one, and the HIGHSCORE on the display at the top of the rack. The menu is part of the scenery rather than sitting on top of it. The 3D "Stack Server" logo with the letters stacked (beige over blue) reinforces the idea nicely, and pairing Tetris style polyominoes with a data centre theme is a combination I hadn't seen and one that makes visual sense, since racks literally are stacked blocks.
I couldn't start it, though. I clicked and double clicked PLAY several times and nothing happened.
Probable cause is the usual one in this jam: the game window is much wider than the browser view (there's a horizontal scrollbar), the rack is clipped on the right, and the buttons' clickable areas are almost certainly offset from where they're drawn. Making the canvas scale to the window would likely fix it in one go.
It's a particular shame here, because with a menu that creative and good looking, the menu is exactly where the player gets stuck. Also worth saying your end of life answer is one of the strongest I've read: completely offline, no servers, no DRM, download and play forever.