The iPhone's always been a great device for small flavorful bites of gameplay -- Canabalt's one-button jumping game probably set the course for this early on, but recently there's been a bevy of titles like these. Super Crate Box, Hookshot Escape, and Ziggurat have all offered up well-polished, simple, but endlessly deep bits of gameplay. And now here comes Spellsword, another great title in the same vein that cuts a specific genre (in this case, the action RPG) down to its core, and polishes it until it shines.
There are two things for Spellsword's unnamed hero to do: Move around, and slash. But those two actions are made complex by collecting spellcards as you move, very similar to Super Crate Box's crates. Not only do they power up your sword, but they send out spells against waves of oncoming enemies, so your goal becomes to move around, dodging all of the various baddies and collecting cards as needed.
One place where Spellsword really does innovate is in its missions mode. There is an endless mode, of course, and that's probably the ideal way to play the game. But Spellsword also has 60 missions to play through, which cut the endless gameplay down into a series of goals, like collect 5 cards, or survive 3 waves of enemies. Finishing missions earns rewards, which then get used in a nicely complex RPG system, allowing your hero to power up as you play.
Spellsword is an excellent game. It definitely borrows a lot from other games (not the least of which are the endless references to all sorts of geek media), but it does innovate with that missions idea, and the RPG elements lend a nice addictive curve to the proceedings. iCade compatibility is a nice bonus, too. Spellsword is available in a universal version for 99 cents right now.