Dog + calculator = OP :D
It's got a nice progression curve with the unlocks. Early on it's tough to find portals, but with better stuff you can get more loot. I think I would've preferred being able to see the full tech tree, so you can plan ahead.
My only complaint is that there's pathfinding. I'd rather just walk into the direction I'm pointing at, since I'm mining everything in front of me anyway. Right now it felt a bit awkward having to spamclick on the floor, especially when trying to go somewhat diagonally.
Pretty fun game overall, good job :D