Had a lot of fun trying out the different map sizes and upgrade paths you could take.
Some of the upgrades felt like they didn't have much impact (like turn speed), so I would use the gold to buy hp-regen to effectively re-roll the shop until I found bullet damage, fire rate, drill efficiency, drill speed.
The start of rounds felt very slow, mainly because of the rocks and waves taking so long to clear.
With some luck, I got some exposed minerals helped jump start some runs.
Record: 21:59 (on the largest map)