Defeating the Queen
The queen ant is the final boss of the game.. and one of trickier boss battles in any game I've played. Once you figure out her weak spot it's actually very easy but getting to that point is tough. Buzz doesn't have a power meter so one hit is fatal, this obviously leaves no room for error. The controls aren't spectacular either and it takes some practice to get them right.
When you first enter the room start advancing slowly, take a practice jump to get used to the timing. Even though this looks like the tunnel level it controls differently. As you approach the queen she shoots these balls of something at you. Stand still and jump when they get close:
Do not shoot these projectiles, that will send them up into a spiral that just lands right back on you. When a larvae approaches you can either jump over it or aim down to shoot it. It's important to learn the difference between aiming down then shooting vs. pressing Down and Button I at the same time - the latter will roll a grenade which usually misses them.
The secret to defeating the queen is to stand just outside of her reach. It looks like she can hit you but just barely misses:
When you're this close she won't shoot projectiles, you could just stand in this spot forever if it wasn't for the steady stream of larvae. Study their timing so one doesn't get you when you're attacking the queen. When one approaches just shoot it:
Now slide a grenade on the ground by hitting Down+Button I:
When the queen bucks up quickly press Up to aim your gun upwards. Shoot her in her now exposed body:
These shots will drain her life quickly. You'll only have to repeat this a couple of times before she's defeated: