Thank you for the positive feedback :D it's very much appreciated!
As for the gun, yes, we also think this but, and there was no way for you to know this as we didn't have time to include this in the game or mention this in the game, we plan on having different gun types which would have a different ability assigned to them.
The pistol that you use in the demo for example would have a Power Shot, where you can hold the fire key down to charge up a stronger blast. A different weapon like a shotgun for example, would have a lower rate of fire but a higher damage output and the ability to knockback an enemy.
As for the environment, yes, very much as you've said the deadline definitely played a part on what we could cram into the fields as exploration. Ideally, we'd very much like to go down a much more Zelda-esque route with this with things such as breakable walls, hidden switches, hidden caves etc which would hopefully make exploration much more rewarding and not so easy. We just didn't have the time :(
Again, thanks for your feedback! We've added your game to our list and we'll be sure to give you some feedback on it when we get to it :D