An 85% discount on an item is a pretty good deal, wouldn't you think?  You could pick up a brand new Corvette for under ten grand.  A nice steak dinner for under $5.  An mp3 download for fifteen cents.  Or, you could pick up a highly polished, deep, and charming puzzle game with an innovative co-op mode for $1.50. 

Last year, we reviewed Arcen Games' Tidalis, and we were quite impressed.  It was an editor's choice 5 point review, which we don't give out too terribly often.  One of the most impressive features was the easy drop in/drop out co-op for local play.  Tidalis can be played with either mouse or keyboard, and if someone walks by interested in playing, they can just grab whichever of the two the first player isn't using.  It's a perfectly seamless system, but Arcen wasn't content to rest on their laurels.

Tidalis is a puzzle game for everyone, from the very casual Bejeweled fan to the hardcore gamer who enjoys competitive play. For readers of this site, co-op is the main event, and the cooperative options in Tidalis are particularly robust, while at the same time very elegant and intuitive.

The beta for Tidalis, a unique co-op puzzler from Arcen Games, launched a few weeks back - but upon initial launch it was missing several cooperative features.  Arcen has announced that the latest version includes multi-well co-op play as well as several other improvements to the game.

It was the end of last year when Arcen Games, makers of AI War: Fleet Command, told us they had two cooperative titles in the pipeline for 2010.  The first was called A Valley Without Wind, which was a take on the tower defense genre.  The game has since been bumped to 2011, but the second was an unnamed puzzle game with an addictive but simple mechanic.  Today Arcen has named the puzzle game and announced a beta starting very soon.