Update: Alarameth TD is being retired from the Steam storefront. Please see details in the announcement at:

A unique, dynamic, challenging, fully-voiced tower defense game for Windows, Mac OS X, and Linux. You begin at Veldamir Castle, a small outpost at the edge of the human lands, where Wynathean the Wizard walks you through your training. From there, you proceed to the elven, dwarven, and gnomish realms in an effort to save the lands of Alarameth from certain annihilation.

FEATURES

• 15 highly varied levels with unique challenges, with a combination of "mazing" and "non-mazing" build areas.
  
• 7 primary tower types (each with 3 levels), unlocked as you progress in the game.
  
• 50 achievements, 7 trading cards.
  
• Heavily story-driven, with each level voiced by at least 1 primary character.
  
• Both 32-bit and 64-bit executables available*

*32-bit and 64-bit editions are only available for Windows/Linux. The Mac OS X edition is 64-bit only. The appropriate edition for your OS will be installed by Steam automatically.