jogosgratispro,
Ofcourse, you can check for gameover.
If you already bought this item, check function "check_col", there is last event inside this one, called "f.Call("has_count") = 0" - this is what you need. 0 - is means no possible block groups (by default, this template append new blocks in this case).
Add levels? I think - yes. But not sure, what exactly you ask: skill level, or just level like level 1, 2 ,3... 10.