I think carefully in the question:
- The most effective way is to add some backtraking to search the best ladder to reach player. Probably from player so you solve all the directions of all the enemies in "one step". But, yes, this add some code.
- Other solution: remember last lader used by each enemy and check if the level of the enemy continue bellow/above the level of player for some amount of time/ticks (or distance of player, or some sort of this). Then use another lader when search for the nearest lader. Not sure if this works.
- One more solution: add areas to the map definition.Imagine you add 8 bits x cell. Each bit  indicates an area in the map. So, you check the player cell and determines he is in the area 3 (3th bit set). Then you known the emeny must go to the lader that have a 3th bit in its cell to reach the player. This reduces the number of levels (but compression must do its job and finally the bytes diff must be minimal).
Good luck

Nice game!
Some notes about it:
- You need to collect all the gold to pass level?, but you must collect 1+gold_view_in_screen to pass level. Maybe by design but it's confuse.
- If you are trapped in a dig you make you must diw when the wall reappears but the game hangs.
- If you make 2 digs one after the other, a bad-boy fall in one of the digs and you fall in the other the game throws a java.lang.ArrayIndexOutOfBoundsException: 433.

It's a good idea. You could have 2 numbers in each cell, the actual big number in the center and other one small in a corner. I'll try to add it. Thanks!

Yes, "Solve" is much more meaningful and the "components" are custom drawings.
You're very right, a "real" Sudoku must have only one solution. (I ignore it initially) It's a "difficult" point. I have modified the game to generate one-solution sudokus, however there are simple sudokus. Maybe the next weekend i'll think a bit more about it and i'll try to generate more difficult sudokus.

Thanks for the comments!

Hello!

You're all invited to play this spare-time sudoku http://icecoffee.biz/java4k2006/sudoku4k.jnlp