I realize this was basically just playable advertising for Fallout 4, but it's quite a fun little game. I do have a couple suggestions for things that could be changed.
1, Vault Door upgrades are pointless. Sure, having a couple extra seconds to get people into position is useful, but only in the very beginning. Once your dwellers have some semi decent weapons raiders aren't really an issue and the door is useless against deathclaws so it might as well be open when they eventually come.
Solution: Having the second tier door keep raiders out and the third tier door keep deathclaws and raiders out would make upgrading worth the caps. As it is, even though it's only a total of 2500, it's essentially throwing caps away. Failing that, adding automated turrets to the outside are of the vault entrance to automatically attack and weaken, if not outright kill the attackers. At tier 3 the automated turrets can kill raiders before they can get inside and can severely wound deathclaws before they get in.
2, Having guards in the vault door room is actually detrimental and cause you to lose even more resources and here's why. A, Your resources start going down as soon as the vault door is breached regardless of what room the attackers are in. B, You can only have 2 guards in the door room so when something comes knocking, they stop in the door room and fight with the guards. Even with really nice weapons, two guards alone can't kill all the raiders before the survivors run off to another room, which takes several seconds. On the other hand, having no guards at the door and the first room after the vault door be a 3 wide room with 6 well armed dwellers results in raiders dying before they even finish running all the way into the room. They're actually dead faster if allowed to simply run in instead of trying to stop them at the door with only two people. Likewise with the deathclaws. I currently have a kill room set up that kills all raiders before they even get all the way into the room and kills a deathclaw and leaves the others so severely wounded that they die within a few seconds of hitting the second room.
Solution: resources should not start dropping until the attackers have passed the door room. This gives a reason to have door guards since they will soften up the attackers (and will even kill some of them in the case of raiders) so that they die that much faster once they move to the next room, thus the player losing less resources.
3. During events dwellers are forever running behind one another making it impossible to click on ones in the back, which usually means dwellers die because you can click on them to heal them.
Solution: A list view for room occupants from which you can select any dweller on the list and force them to move to the foreground so you can click on them as well as heal them and administer radaway from that list.