Full Frontal Assault is a mixture between tower defense and seek-and-destroy missions. It's not meant as a full title, so it's pretty cheap to pick up. I got mine Day 1 for $30, I believe. Great game.

Also, if you're enjoying Crack in Time, you'll probably
love Tools of Destruction. I felt ToD was the best title on the PS3.
I remember reading an article about the lead developer on Dragon Fantasy a while ago, when it came out for iOS/Android. It got good to positive reviews back then, and they've added a "16-bit" mode to "spruce it up" for the consoles. The general consensus that I've heard is that if you like the old NES/SNES RPGs like Final Fantasy or Dragon Quest, you'll probably really enjoy this. From the storyline, it sounds very similar to Dragon Warrior IV. I'll probably put up one of my little mini-reviews once/if I beat it.