Well, I had a game up and running, and the soft "plunk! plunk!" was kinda hypnotic, but there was no challenge. Did adding an extra specie of egg help?
Well, it wasn't a bad idea, but the game was still too easy. "Deadlocked" boards almost never appeared. The problem was really that most puzzle games use increasing speed as their difficulty level adjuster. In Tetris for example, or Lumines, the pieces drop faster and faster as you progress through the levels. But Omelette lacked this option — I really didn't relish the idea of having to race against a clock by hammering away at the little controller — guaranteed to raise anger levels, not entertainment. Besides, what can you do as a player to avoid "deadlock" anyway? It's not really under your control, and that's never a good way to treat your players.
So I introduced "health" as an alternative way of ending the game. Each move you made, you'd lose a little bit (gotta watch that cholesterol, I guess). Simply matching up eggs wouldn't gain you any back — after all, you were expected to do that on each move anyway. No, you'd have to plan ahead and play for style, aiming for "combos" and longer rows of eggs, to regain health.
This immediately added an "edge" to the game. "Dammit, I actually have to think now!" Success!
My beta-tester (girlfriend) kept on racking up health like some kind of fitness fanatic. The problem was that Omelette had no difficulty-curve, just a perfectly flat difficulty-straight-line. Tweaking the rates at which health went up and down wasn't the answer because that would just move the flat line up or down — there would still be no progression. You'd either get clobbered instantly and unfairly, or else the game would go on forever.
Well, walking home through the park one evening, I was thinking about all sorts of complex "special tokens" that could drop into the grid, that the player would have to deal with. Weird frozen Yeti eggs (that abominable snowman must be a monotreme, like the duck-billed platypus) that would start to 'freeze up' other eggs nearby until you thawed them somehow... all sorts of craziness.
Then sanity prevailed, and I decided to try The Simplest Thing That Could Possibly Work: dropping in "blocking" pieces that would merely get in your way, and couldn't be matched up in the usual way. These would not appear at first, but be more frequent later — now we had progressive difficulty! And when I decided on "dropping them off the bottom" as the mechanic for getting rid of them, this introduced two new aspects to the design:
At which point, my work was done! Well, apart from all the polish, of course... tracking high-scores, instructions, a jokey "spotter's guide", some credits (mainly to thank those who went before me in exploring the Apple TV), documentation, packaging, a main menu icon, screenshots and a web presence. Oof!