Dragon Forever is an action game developed in Java by William Swaney. You can play it online (via "Java Web Start") or download it from this page. The goal of the game is to survive as long as possible. The closer you are to a unit of the castle, the more damage your flames do. Each time you’re hit you get a time penalty. When time runs out, the game is over. There is composed by an infinte number of levels that become more and more difficult.
Willian is editing an excellent blog (in english) to talk about his games (4 until now) and about casual games in general. Visit it!