I really enjoyed this (even wishlisted it on Steam)! If I may, I have two suggestions for you:
1) Let the player know what each resource looks like from the start (it could just be in the instructions menu before the game begins).
2) Maybe have the dome be battery-powered to add an extra layer of difficulty once a player upgrades to a second laser.
For my first point, I found myself confused during my first attempt because I didn't realize that the little icon for the Auto-Repair upgrade represented a type of resource (sand). I didn't get the resource counter upgrade at the time, so I didn't know what it was (the same thing applied for the resource for the fruit upgrade).
As for my second point, I found that once the second laser was added, a lot of tension was gone because I could just hold down the spacebar and move the lasers around, killing all the enemies before they could even get close to the dome. My suggestion is that if the dome is battery-powered, it could have no trouble maintaining a single laser, but a second laser would drain too much power. So, either the player would have to mine for a specific resource to maintain the battery's energy OR the lasers would have a cooldown period of a few seconds (either synchronized or separate). If the former, the resource wouldn't even have to be something new, it could be something that's already being mined, but the player has the option to either use it for the battery/lasers or something else.
Anyway, those are just my thoughts and feedback. For all I know, you may have already thought of this or someone else told you already... If that's the case, then I apologize for the repetition. In any case, I'm eager to play the full version of your game with whatever the final features end up being!