Version tested: iPad
Have you room in your heart for one more touchscreen tower defence game? If not, well, could you try and make room? Radiant Defense is really pretty and really smart, see. It's a treat to play, and it doesn't even let the freemium model ruin all the fun.
You know the drill: wave after wave of creeps are spread across a series of maps, and you've got a range of different turrets to place in order to protect your bases. Radiant's turrets are great, but it will take you a while to try them all out. A handful of the more basic offerings are available from the start, while a second tier will require the placement of a costly research unit in order to unlock them. A third tier will only become available if you opt for some in-app purchases.
This isn't as bad as it seems, though. There's still a decent selection of gadgets to knock around with regardless of whether you pump any money in, and there are only a handful of IAP packs anyway, meaning that even if you do bust out the credit card, you're not going to be paying much more than a few pounds.
The game's wonderfully punishing whichever option you take, but I fought my way through a decent chunk of the campaign using nothing but the four most basic turrets: regular shot, laser, cannon, and a debuff thingy. I had been playing for so long, incidentally, that I'd actually quite liked throwing the developers some money, regardless of what I'll be getting in return.
Turrets can be upgraded, and there are plenty of nice combinations waiting to be discovered: I tend to chuck a laser in early to take care of any shielded enemies, for example, and then follow it up immediately with one of the less precise cannons, too, to shred those horrible aliens when their defences are down. On top of that, most levels will steadily give you new wall module pieces to place on the map as you play, meaning that you build mazes, altering the creeps' paths and stringing them along a little as the action starts to heat up.
That's often as deep a strategy as some tower defence games will offer, but Radiant mixes things up a bit more with a number of enemies that recharge their health if they're not under constant bombardment. By all means extend their route to the goal, in other words, but make sure you keep your firepower on them as you go, or you'll just be giving them a chance to recover.
On top of such clever elements, the whole thing looks beautiful, too, with wonderful neon colours and a delightful selection of gloopy things to chug away at with your weaponry. Moody robots, space snails, something that seems to be based on a bolus of soft scoop ice cream: you never know what's coming down the pipe next, but you can bet it will give you a handful of unexpected problems when it arrives.
Radiant Defense, then: it may just be enough to replace Fieldrunners as my go-to smartphone tower defence fix. It's gorgeous, it's deviously balanced, and it's winningly generous with it. You have no excuse not to give it a spin.
App of the Day highlights interesting games we're playing on the Android, iPad, iPhone and Windows Phone 7 mobile platforms, including post-release updates. If you want to see a particular app featured, drop us a line or suggest it in the comments.