I just played dj31. Here's some feedback:
- The length of the level seems right to me: It's challenging but not too long for it to get boring or frustrating.
- The UFO sound effect sounds better but...
- The volume ramp from zero-to-max may be too slow. How about skipping every other step (i.e., For i = 0 to 15 Step 2)?
- The "left over" sound after the UFO effect (when it sticks on a note for a second), is not very appealing. Perhaps it should just stop at a lower note.
- Still needs the tractor-beam sound effect.
- I would recommend making the length of the level meter (not the level) longer (preferable, if possible), or at least lower it by one row on the screen.
- The cloud counter now goes up to 12. How about making it go up to 50 (without changing the length of the level), so that you can treat it as "kilometers" to the Stratosphere (50 km)? After all, everyone knows that UFOs hang around in the Stratosphere.
- The jump mechanic seems very stable and natural.