There's a lot of buzz around cloning apps lately. Zynga recently received some flak for making a clone of Tiny Tower, and there's a big lawsuit around Triple Town and its clone Yeti Town. I would argue that there's a right way and a wrong way to clone an idea. Blatant rip-offs are obviously wrong. The right way is to lovingly borrow some of the core mechanics of a certain game, but add in your own aesthetic, insight, and style.
Blot is an example of the latter. Ostensibly, it's a clone of the very popular Jetpack Joyride. You play as a little ink blot that's flying along, tapping the screen to make it rise, fall and collect power-ups and coins.
One could argue that Blot is a ripoff of Jetpack Joyride, but aesthetic is unique, combining some beautiful hand-drawn environments with a bouncy, joyful soundtrack. The game employes new ideas, too. For example, the inky spot can combine with colors for extra abilities, and the upgrade system is even more complex than Jetpack Joyride's, allowing you to pick up mechanics that can completely change the way the game is played.
I would also argue that Blot's rewards are too spaced out. Even after several runs, I haven't collected enough coins to "buy" anything interesting. But everything else in the game is very well done, and the little add-ons (like Blot's hilarious costumes) are worth chasing down over time, even though that curve is steep.
Blot is available now for US$0.99 as a universal app. It does borrow from Jetpack Joyride and what you might call the "hover Canabalt" sub genre, but its infectious style and unique features make it worth a download.