Fun little game, I like the idea with the special blocks making it increasingly challenging.
Some notes:
- It's hard, could easily start of easier. And with a tutorial... you know... arrows and text... like "grab the blinking block", "move it away from the tower", "grab the sticky block", "watch it all fall to pieces".
- It's not particularly pretty, but more importantly... it doesn't communicate very well. Others have commented the outlines, and I agree, but I'd also add that the design of the block probably could be made to communicate the block's properties as well.
- It took me a little while to figure out that I need to move the blocks far enough away from the tower to get rid f them. This should probably be mentioned at startup.
- Controls with mouse+keyboard are fine, but feel a bit... "gamey"? Could the act of removing blocks maybe be made to feel more "physical"?
- Music fits well but I perceived them as repetitive fairly quickly.
There's potential here for a fun little time waster, I had fun playing it! I think the upgrades are a good direction for extending the basic game, but I think one could probably find quite a few more physical mechanics to extend the gameplay further. Good luck!