i made a 3d game after making many 2d games with XNA. i used Unity this time. i can not explain the idea behind the Nega Kon! , so i paste the description from IndieGames :
"Nega Kon is an Experimental Gameplay Project submission with a rather clever idea - somewhere in each level is an object that you need to fix, so that you can collect a star before proceeding to the next stage. This object appears flat at first, but pressing the X key while viewing it from a specific angle will turn the object into a solid shape. Players can then utilize this new entity to grab the prize and finish the currect level.
There are also only a handful of levels to play through, so most of us would make short work of it in just a couple of minutes. The download links for Nega Kon are available here. (Windows, 6.10MB)"
Download Nega Kon! from here here.
Nega Kon! is reviewed in many gaming websites ( and in many Languages ) :
Game-Damashi ( Japanese )
indievault (Italian )
doupe.zive.cz ( Czech)