You'll start out on the ledge at the far left with a nice little flip, but you can either go into the water (it won't kill you) or stay on top. I'd recommend that you stay on top just because I find that it's easier, but it's up to you. Either way head right and kill the Sniper on the bottom ledge near the water ahead. Hit the item container for a machine gun. Not long after an item capsule will fly by, hit it to get a rapid fire which will be useful with the Machine Gun. Another Sniper will be waiting ahead at the bottom, kill him the same way you did the last one. When you reach the bridge you’ll have to avoid the newbie mistake: walking or rather running across, and I can tell you right now that you’ll never make it. Jump across it instead.
There will be another bridge right ahead so do the same thing there. Once you’re on the opposite side, a turret will be waiting for you. Avoid it and move on if you’re on top but you’ll probably have to destroy it if you’re in the water. A little ahead two Snipers in a row are hiding the underbrush. You’ll be able to see their heads peeking out from the grass so there’s no surprise, just kill them when they get up. An item capsule will fly by soon after, it contains the spread gun. You’ll only be able to get it if you’re on the top unfortunately, but cheer up, you can get another spread gun later on. Until you die or change weapons, you’ll be a killing machine to the weak enemies in the next few stages so you’d better make use of it.
Kill the Sniper on the ledge ahead then drop to the lower ledge where the turret and item container are. Destroy the turret but don’t get the contents of the item container if you have the spread gun. Now drop into the water and wade to the right onto the bottom ledge and destroy the turret to the right. Jump to the narrow ledge ahead then to the high ledge to the left and destroy the turret that’ll pop up. After that, kill the Sniper on the opposite side of screen ahead. If you don’t have the spread gun, destroy the item container under the ledge to get one. Yes! An item capsule will appear from the left that contains a rapid fire, you can get it if you want.
Further ahead there will be series of ledges, jump to the top then continue right. Don’t destroy the two item capsules that appear here if you have the spread gun; one is a laser and the other is a rapid fire. Mosey one to the right and destroy the turret that appears on the far right. Once it’s gone jump forward and destroy the turret ahead. Now jump over to the left and then fall off the right side to the bottom and destroy the turret beside you. Now all you have to do is walk to the right and the screen should scroll to a huge structure with various armaments. Yup, this is the boss. It may be imposing but it’s a real weakling.
First things first. Kill the sniper perched on top the structure because he'll be a pain if you don't. Once you've done that, you'll have to destroy the two turrets above the door. The safer way to the do this is to duck and fire on the top left or the middle ledge, which will be way out of range of the turrets. The slightly more dangerous way to do this is to drop to the left side of the slightly higher ledge closer to the structure than the middle ledge proper and fire from there. After they’re gone, destroy the door to finish the stage.