Innovation doesn't always come in huge leaps and bounds. Sometimes, small ideas start the ball rolling. Little changes and new ideas can turn a simple game into something much more impressive, and in doing so move a genre forwards.

That's what Anthill: Tactical Trail Defense is trying to do, taking the basic structure of a tower defence game and adding to it here and there with some intriguing new ideas of its own.

It's not a complete success, but it's an interesting try, and it's likely to offer gamers who've become a little jaded with the parade of tower defence clones on the market something new to get their teeth into.

Insecticide

Surprisingly enough, the game puts you in charge of an anthill. It's your job to protect it from invaders, gather food, and make sure your colony survives. Attackers come in waves, and you have to fend off a set number of these in every level.

You're constantly attacked by ladybirds, beetles, and all manner of other unpleasant creepy crawlies intent on stealing your sustenance and and destroying your well-tended mound. To counter their advances, you have a number of units at your disposal.

Soldier ants are your brutes, and will attack anything they come into contact with. Spitter ants offer artillery support, spraying out vile blobs of goo at attackers. Bombers are flying ants that drop explosive cocktails, and workers are there to clean up the mess and bring in the food.

Food takes the form of small grubs and the corpses of your slain aggressors. The more food you bring in, the more ants you can produce, the more ants you can produce, the better defended your anthill.

How do you make a pheromone?

The twist lies in the way you send out your troops. Rather than just placing them like you do in standard tower defence games, here you trace out pheromone trails for your ants to follow. It makes for a much more engaging experience, as you try to balance offensive trails with food-collecting trails.

It's an interesting mechanic, and it only comes slightly unstuck when you're trying to delete some of the trails. You hold your finger down on a trail to get rid of it, but if you've got two close together, making sure you get rid of the right one can get a little fiddly.

The game's nice enough to look at, without any real visual fireworks. The screen never gets too cluttered, and scrolling and zooming let you keep a close eye on the action.

Antsy climax

Where Anthill: Tactical Trail Defense falls down is its difficulty setting. There are some severe spikes later in the game that are hugely frustrating. It sometimes feels like there aren't enough units, and that a couple of different ants would keep things fresher for longer.

That doesn't take away from the fact that, when it's on song, Anthill: Tactical Trail Defense is a smartly designed, intelligent riff on the tower defence genre. It's not without its problems, but it's original and enjoyable all the same.