MicroSweeper is Minesweeper-like game implemented in Java and intended for J2ME-capable (MIDP 2.0, CLDC 1.1) hand-held devices. It provides an additional determinism: a game mode where all mine locations can be deduced from neighborhood count and you are not forced to place a guess. It has some extra goodies: walls, 4, 6 and 8-neighborhood boards, and wrap-around (torus) boards.
The game is licensed under the GPL 3. It needs MIDP and CLDC libraries to build, and a non-free preverifier has to be run on built binaries. All of these are available (free as in beer) in WTK, SUN's Wireless Toolkit package. As far as I know, there is no free implementation of these, and in particular they are not part of SUN's recently freed java package. I checked the following document, and it seems that this state of the matters doesn't interfere with GPL 3: http://www.fsf.org/licensing/licenses/quick-guide-gplv3.html (Check "New System Libraries Exception" in particular.)
The game doesn't use any other (free or non-free) libraries. It uses GNU Make for automating the build process and OpenJDK's javac and jar are used to do the compilation and packaging. A preprocessing using GNU M4 and Python takes place during the building process.