It is a pretty hypnotizing experience. Once you get into the rhythm of digging-upgrading-revealing map and enemy fighting it is quite engaging. I like these weird structures that you can uncover. At the beginning I was sure it's all about digging up minerals, so when I found out you can have different shrines and other, destroyed domes with permanent upgrades suddenly revealing a map was much more objective driven.
I went with maximum offense - bombs + fire, with magnets mounted on the dome. I was stubborn to not upgrade carry weight and speed until before last wave, because I was hauling my loot to the nearest spot that had magnet reach. Bombs and fire take a long time to deploy, with my breaking strength quadrupled it was barely handy, but it was also my fault to not upgrade them for a long time. I didn't even have a a chance to see bombs with higher radius and splinter bomb as I uncovered that one BIG orb very soon afterwards and then I had a launch sequence.
I'm not sure 1 bit graphics gonna sell it. I understand it's supposed to be a small scale, lo-fi, easy in-easy out experience but still, something feels off. I'd try to make sprites bigger, or rather increase the resolution and size of sprites so they convey more details. Right now mixels are really visible, and I think that is bothering me subconsciously. Add special items that are colored differently? I think the presentation right now is the weakest element.
I wonder what are you cooking with missions? With proper background and lore the game can be even more engaging. I'd also focus on adding unique structures that can be spawned randomly that add boosts, maybe even permanent between missions. A secret objective-puzzle like in Spelunky would be also a great addition.
Looking forward to your updates!