Popular touchscreen tower defence game TowerMadness has received a mammoth new update, which features improved visuals, more maps, and some minor tweaks.

First up, the game now supports the Retina display screens on iPhone 4 and fourth-generation iPod touch, meaning the 3D strategy game looks sharper and better than ever.

The update also brings five new maps, which are completely free. There’s Delphi - A Visit to the Oracle; Dune - Sands of Eternity; Enigma - A Twisted Puzzle; Pinball - Set the Record; and Pitchfork - The Farmer's Fight. To help manage the game’s huge array of levels, the map list has been given an overhaul.

There are also a handful of tweaks and optimisations, including more accessible leaderboards, a bug fix for Game Center, a new startup screen, and no more Christmas graphics.

The developer calls it the “first” big update of 2011, so look forward to even more alien-attacking content throughout the year. TowerMadness is out now iPhone and iPod touch for £1.79 / $2.99 / €2.39.