Shields of Gemland is just another "Puzzle Bobble" clone. You control a canon that shoots coloured balls and you have to match 3 or more balls of the same colour, yes, same old, same old - the picture is self explanatory. It's a good time waster, it has an upgrade system and the graphics are quite pleasant. The only levels that are "challenging" are the "puzzle" levels, in which you have to clear an entire board using a given number of balls.
Play it on King.com