Vertigo Games' puzzler Shellblast is on Game Giveaway of the Day again, and you can get the $4.95 title for free if you download and install it within the next fifteen hours or so.

In Shellblast you play as a member of a bomb disposal squad who has to disarm explosions planted at landmarks and important locations all around the world. Described as a mix between Minesweeper and Picross, the bomb defusal part requires you to mark all piston tiles on a bomb correctly before time runs out.

One issue with the game is that the text can be slightly difficult to read on certain wide screen displays and high resolution desktops, but everything should render correctly if you switch to windowed mode to play. A HD version of Shellblast is also available to download and purchase from the Xbox Live Marketplace.

Shellblast isn't the only game that is being given away for free this weekend though. The Totally Tiny Arcade offer is still going on until Monday, so there's a bit of time left for you to grab both of these games before their promotions expire tomorrow.