It is actually quite possible. As a part of our Masters Thesis, we have ported a game I made last year using Flash,
Fire!. This conversion was made as a proof of concept that it is possible to create shoot'em'up games using our library.
This game now runs perfectly on our phones, the Nokia 6600 and the Sony Ericsson K700i. We haven't tested this game on other devices yet, but we assume that this game will work for most MIDP 2.0 based phones.
