Also, Meteos levels do vary in more than size, the gravity changes, the mix of colours changes and in some levels, the whole mechanism to make them fly does too (gravitos level, requires you line up three which blow up but don’t travel. before the charred blocks are recoloured, you must line up three ABOVE them to send blocks flying).

The thing that I find interesting about Dr. Mario is that it takes the Tetris mechanic and turns it into “combat.” I think this little difference helps make Dr. Mario slightly (and I mean *slightly*) more rewarding, as when you complete a group, you get to “kill” something. Of course it’s only goofy, cartoon killing, but it’s killing none the less.

I bet you could do the same for almost any of these variants. Turn the “blocks” into something halfway recognizable, and all of a sudden each removal becomes more rewarding and more fun (with the right sprites and sound effects, of course).