Brent Simmons found a great Tetris clone for OS X: Quinn, by Simon Härtel. The gameplay is exquisite, featuring configurable keystrokes, smooth animation, and a neat (but subtle) “bounce” effect when you drop a piece from the top. Quinn is faithful to the original game — as Brent writes: no dumb “innovations” or anything. Right on.
Quinn even supports Undo, which though I suppose technically constitutes cheating, comes in handy when you inadvertantly drop a piece one column off from where you intended. It’s just a great little Mac app. It doesn’t have help (and doesn’t need it), but Mr. Härtel had the common decency to remove the Help menu entirely, rather than leave behind a single vestigial menu item that brings up an idiotic “Help is not implemented for this application” dialog box.
Oh, and it’s freeware.