I am sure your being honest to the OP but you could have posted something more constructive.
I wish the viewing area around the player was larger. Right now it moves one square with the player and it can be confusing to keep up.
yeah I was meaning to come back and elaborate.....
for starts, the color scheme is dreadful. Its 2008. monochromatic setups are a bit... done. I realize there are SHADES, but this is like, gameboy quality color.... it leaves a bit to be desired...
it's disorienting. its what a 5x5 tile screen?... each move results in very choppy and confusing movement.
to me it functions like the following classics, only far inferior in terms of playability, visuals (...which is kind of .. scary), and overall fun factor...
Starting with my all-time favorite of this style
Gateway to Apshai, and the other Temple of Apshai games...
Telengard
Sword of Fargoal
Rogue
Ultima
It plays like a dumbed down version of the above. I say this because well, all of the above mentioned are from the mid 80s. Key things these games have that yours is lacking: (I will be omitting the epic 100+ hours of gameplay from Ultima, for obvious reasons... but the tile based engine is vastly similar to Dungeon Diver...... I speak mainly of Ultima 1 and 2 since they contain the single character hack slash . 3 and on involve turn based strategic battles with multiple enemies....)
anyways:
All of these games have more color depth, even on the commodore 64 release. Gateway to Apshai featured blue walls, red doors, gold unwalked-on dungeon areas, FULL motion as opposed to tiles...
Telengard again featured coloration, and it really has similar gameplay to your game... only it's got more staying power...
Rogue, in it's IBM release, featured more color, more visibility, more to do, and more depth..... with ASCII characters.........
and they all utilized the full screen. not a crummy JFrame
not to mention, the playability is better because you arent going from mouse to keyboard, and what have you.
Rather than use JButtons to do battle, why not use action listener's for key presses..... you appear to be attempting a retro game, yet make it more cumbersome to play than need be. The combats themselves are somewhat useless given that there is only an Attack option. defend, items, and magic would lend more to it. For your setup, simply attacking the little blobs would suffice. The dialog boxes seem useless.
Bottom line I guess, expand visibility, add some color, get rid of the mouse....
I know you're using Java, and using all the swing components like combo boxes and what have you, but cmon' what games honestly use stuff like that...
maybe you should switch to a different language.... you could honestly write a better game in assembly, or one of the many versions of BASIC, such as QBASIC, or Dark BASIC....................
as for your obvious desire to multiplatform... SDL is a good choice, as games like Daimonium use it and achieve multiplatform implementations.....
there is also OpenGL but that's a bit excessive, or Allegro.