Apps Core game loop suggestion needed

[IPSUS]

I have developed a 3D puzzle prototype codenamed "The Hole":

The basic goal is very simple - you have to turn the falling figure with finger(s) so that it will fit into the hole. You can use rotation gestures with 2 fingers and can rotate camera as well.
Currently there are 2 game modes - survival and evolution (pass 10 holes and make as much score as you can). Of course, release version should have some bigger goals than just these 2 simple game modes.
Currently I have 2 additional gameplay loop ideas:

1. Highlight a 3D tree of possible combinations of falling speed and cubes count. Each time a player passes the hole with a specific combination a tree node highlights. If pass is clean then highlight is brighter. The ultimate goal is to grow up this tree as thick and long as possible.
2. Split gameplay into several layers of complexity - 90 degree figure turns, 45 degree turns, smooth turns and finally build figures from more complex meshes rather than from cubes. Passing some steps in simplier complexity layers will open access to more complicated layers. This can be combined with a tree from previous point.

The gameplay fits well for slow paced "dzen" style as well as fast paced hardcore style for brain geeks.
I would greatly appreciate any feedback and suggestions about this game and particularly about the core game loop as well as the ultimate goal in the game. Thank you!
Note: the game is in prototype stage so it might not work on all Android devices. It has been tested on Sony Xperia Z2.

Download link: http://anrael.com/files/TheHole_0.1a.apk