The sound, graphics, and general gameplay are excellent. Now on to the two major issues which make this game essentially unplayable past a few minutes.

1, Why does my blaster have an over heat function? It serves no purpose as its default fire is just strong enough to serve as a last ditch weapon to keep your self alive for a few extra seconds. There is no reason for this weapon to have any kind of leashing mechanic. Especially when you are expected to defend multiple rooms at once. In fact this gun needs to have a few UPGRADES.

2, Resources, why do the enemies drop such a small amount of metal? Do you really expect people to repair four separate targets, micro manage turrets, relocate turrets, and all while defending three separate locations? This is an absolute mess, and a few sub systems need to be axed badly. There is no reason to have a situation where you need to relocate resources on top of arranging the best defense method for each individual room. Have one or the other, but don't have both as they are contradictions of each other. When you set up turrets have an upgrade that allows you to change it into any other type on the fly without need for disassembly and relocation. Increase the resource drops by at least a factor of three.

Now those are the major issues that make it unplayable. As in don't expect a person to last past the ten minute mark. Now for less serious, but still valid considerations.

1, Have enemies that focus on the player more. I was never at any point in risk of dying myself.

2, The three stages got boring really fast and I think the game could use some form of procedural generation.

3, Weapon upgrades could really expand your active participation in the defense, which is essentially nothing at the moment because of the pointless over heating mechanic.

4, You have platforming elements but you don't have any thing to platform around. Some stage hazards could really force you to keep your guy on the move.

Anyway, great potential right now, but it really needs a lot of work before I think it's ready to be sold to people for real money.