GemDrop is a free java applet game which seems to be a cross between Tetris, Diamond Mine, and Bubble Bobble. You drop gems in from the top like Tetris but there is only one gem at a time that you drop and you must line up three of the same type of gem next to each other for them to disappear and you earn points. The screen in inverted on Bubble Bobble but feels a lot like the same type of puzzle game. The graphics are professional and colorful so give it a shot if you like any of the other three games I mentioned.