There is an easy to circumvent bug that makes the first layer of stones nearly invulnerable sometimes.(goes away with escape press and new start) 

A small bug that does not properly display research points when you open the shop. (visual I presume fixes if you spend some research points)

A beneficial exploit I can force by getting too fast to the bottom of the screen (usually with laser and bombs) it can be made to scroll endless sometimes without limit but I can't due it reliable so not entirely sure on all conditions.

Minor visual bugs are some numbers in the research window that show wildly overinflated percentage numbers (I presume).

I like the general mechanic and gameloop how the tools bust the blocks is satisfying.

Some convenience maybe missing a button to instantly spend the full ores for a skill in the research left, it gets tedious 700+ ores.

The gold gain options which you can choose each run in the center feels somehow not strong enough because really +120% is nothing in compared to the other options I really have no damage problem but didn't try to destroy as many asteroids as I could. 

Finding other stuff or choosing to have the hammer hit 2x2 on impact for a run would be interesting.

Running for the multiplier gems was fun initially but later I did it on idle.