Are you going to add music and sounds to the next one? (if there is going to be one) i think that music and sounds complete a game and move it out of the beta stage into the final stange (my opinion)
Nice music Diggerguy 3 i wouldn't mind listening to it during the game (actually I currently am but the lack of drilling sounds gets me every now and then)

Well, there was music in MLU1, but it was very buggy and took a lot of space so I removed it from MLU2. Until I find a stable Java library for playing compressed sounds, there probably won't be ay music in MLU.
Besides, don't you find game music annoying, since it's the same stuff on and on again for hours?

You can put lots of music say 30 minutes. Also 5 MB is quite small.

If you could have like 30 minutes of music, that would be:

12,500 KB for 7:30 music.
12,500 KB x 4, because 30:00 : 4 = 7:30
12,500 KB x 4 is 50 MB.

NO.

Well, in 128kbps mp3, 7:30 is about 7MB. If its not compressed, its at least 5-6 times larger without really affecting the quality.