Also On: PS4
Publisher: Smartphone Labs
Developer: Smartphone Labs
That's pretty much all there is to say about it, to be totally frank. If you've played one of them before, ever, on any system, you'll have gotten the full experience of what this game has to offer. The Keeper of the 4 Elements doesn't add in anything new, nor does it throw in some crazy twist. It just gives you a map, a variety of enemies moving along set pathways, and towers of varying abilities. This isn't a game looking to reinvent the wheel.
The theme, such as it is, is that there's a wizard involved, so that explains how you get towers shooting the titular four elements. It also covers why you can summon storms of various sorts. I guess if that's the kind of thing that's bothered you about other tower defense games, you can be happy The Keeper of the 4 Elements answers your question. I've never stopped to ponder that, so, needless to say, it leaves me indifferent.
In fact, as you can probably tell, everything about The Keeper of the 4 Elements leaves me indifferent. There are about a dozen other tower defense games on the Vita, and this one does precisely nothing to set itself apart. It's neither good nor bad enough to be memorable. It's just there, ready and waiting for the day someone says to themselves, "Might as well have a tower defense game on my Vita." When that day comes, this game will be here, waiting as unobtrusively and blandly as possible.