As I still don't have my 8X back (A(*F&8af7), I can make some quick suggestions based on what I've seen so far (via pics).
- The color bar at the top is useless? Remove it;
- The 3D graphics are not so great, I suggest making them look better;
- You could drop some coins into the well (rarely). With them you should buy things such as time slowdowns, new character, new well (maybe?);
- You could also put some objects that should be related to achievements (so you can make more);
- As you complete achievents you should get a combo bonus +1 x points for every 15 achievemnts?;
- As deep as you go through the well you should earn points (that way the game will become more challenging and less boring, as you'd want to beat your/friends highscore/s).
The last 2 suggestions would work with an endless version of the game (as you keep falling).
-The color bar is explained in the game. It shows the objectives for the level.
-3D graphics look great in motion.
-Coins are in the well and they do cause special events to happen.
-Certain actions reveal new aspects of the game so there are a few "Achievements".
-The game is time based. The faster you beat the level, the better your rank. The leader for each level is displayed on the level select screen so you know what score you need to beat.
Looks like I have most of your suggestions covered.
Thanks for the suggestions though.