Round 4 is probably the one round in the game where you can easily get lost- unlike the others, the two rooms here basically look the same. One has a pale blue background, the other has a grey background. Try not to get lost. You'll get the Jetpack fairly early on, but this is a pretty tough stage because of the new enemies, which probably exemplify the game's problems. First, the weird hopping UFO things will get in your way, but shooting them causes them to blast off and zoom ahead, usually in your direction. Don't shoot them at close range, either avoid them or take 'em out from a distance... Which you'll struggle to do as you usually find them in cramped areas. Thanks, Sega. There's also the snail enemies (I like to imagine it's the snail from the built-in Snail Maze game, out for revenge) that, when shot, turns around- if you shoot the shell, your bullet bounces back and can hurt you! Also, you're still pestered by the lips and the skull, the latter being more annoying now as its bullets will travel across platforms when they land.

At the end of the first section, you'll encounter these little butterflies. They get their own paragraph, because you need to kill all these guys to get the Star Power to appear, and they need to be approached the right way... By that I mean from as far away as possible. When you land the first shot on one of them, they'll fly around in a demeneted Z/S pattern at top speed. So, you need to be far away from them so they don't crash into you, but not too far away as if they wander off-screen, they'll magically reset their position on the platform. It takes a few shots to take down each one, but take them one at a time, then go through the door to take on five more of them. It's a good thing I've got a row of screenshots showing both the first and second rooms here, otherwise you might get the two mixed up. Easily done, isn't it?

The rest of the grey room is much like the blue room- snails, skulls, and those annoying UFOs- so let's just get straight to the boss. Right at the very end of the room, it's... Oh. It's a giant version of the butterflies we fought earlier. It'll move up and down for a while, then eventually do a figure-eight motion across the screen, before going back to up-and-down movement. Almost 20 years before Gears of War popularised it, you've got to use a cover system to beat this boss!... Well, OK, not really. What you need to do is use the lowest platform in front of the butterfly as a sort-of cover- it'll deflect a few of the bullets heading your way, and the others you can move up or down to dodge. Keep your head down when it does its figure-eight movement, and just keep plugging it with lead, and it'll eventually fall, leaving the key for you. Let's get out of here...

... But before then, it's bonus room time! The way into the bonus room in this round is in the grey room, on this set of platforms. All you have to do is kill the snail... You shouldn't shoot too much, though, because remember, it'll turn around and reflect bullets back if you're not careful. Wait until it reaches the edge of the platform and turns around, then shoot again (or, if you're in a hurry, shoot it, float over it then shoot it again). Once it's dead, it won't respawn like the rest of the enemies. Head back into the door on the left...

... And here we go, the bonus room. Exciting, isn't it?

Back in the blue room, head right and the Star Power should appear by these platforms.

If it's not there right away, shoot a few enemies in this area.

As long as you killed all those butterflies, it'll show up.

Once you've got it, the exit's back at the start. Run. Run quite fast. You'll be chased by the blue ghost things.

After all that fuss on the last stage over getting a promotion, it's nice to get to Colonel in one piece.

Once you reach this rank, your bullets change to waves. This'll be handy in the next round.

Hope you didn't get too comfortable with the lack of pits in the last round- Round 5 brings 'em back for its first room with gusto! Also, the balls from Round 3's pot room come back with a different function- they'll fire out slowly in a spread pattern rather than pop out and adhere to gravity. They're easy to avoid, though, and an invincibility missile appears very early on, so just don't fall! It's especially important not to get shot in mid-air, because the stun animation will make you drop like a stone. And die.

Incidentally, I wish more of the game was like this- less enemies, more platformin'.

Once you reach the end of the room, just shoot the underside of the pot a couple of times.

This is just to save you a few precious seconds later.

First thing's first, in the blue stone room, shoot the blocks Mary's shooting in this screen for the Star Power.

Your next order of business is the gap under the platform where Mary is in the shot on the left- shoot it to reveal a power drink. This room is much like the blue orb room from Round 3, but if you got enough points for the wave gun upgrade (and, if you've been visiting the bonus rooms, you really should by this point) it'll be pretty easy- you'll take out more blocks with a single shot because of your wider shot. Unfortunately, this room feels a lot longer than the blue orb room because of the enemies- if you thought the UFO enemies were annoying in Round 4, you now get to deal with them in very confined spaces. Good luck with that. Additionally, bouncing silver balls will keep appearing, which are an annoyance too because of the close quarters. Your best bet is to try and power your way through and destroy blocks to give yourself some room to breathe. It can get quite claustrophobic in here...

At the end, you'll fight the boss- a weird dinosaur thing (citation needed) who fires those silver balls at you. He can only be hurt when his mouth's open, and he'll ocassionally stop opening his craw altogether if there's too many balls on screen. What you'll want to do first is clear some room, and destroy the blocks as shown in the screenshot on the right, which will lead the silver balls below and out your immediate line of fire. If you like, you can also destroy the vertical pillar on the right side to clear even more room, but in any case, get close to the beast and plug its mouth full of lead while avoiding its balls (ooh, matron). Keep at it and it'll drop the key, so you can just go through the exit below!

... Ah, but what about the bonus room? If you want to go for that (and you should)...

You've got to go back to the entrance and go through the door, then go through the door again.

If you shot the underside of the pot in the yellow room like I told you to, you should end up here. If not, shoot it some more.

The only problem is, if you go to the bonus room, you have to trek through the brick wall room again. Oh dear~

Now Mary's a General! This means your firing rate has been increased, it's the final upgrade.

So... Did you get all the Star Power items from the previous rounds? Then you'll move on to Round 6.

If you missed any, you're forced to replay Round 5 until you've got five of the damn things.

Here we are, the final battle for space colony Nine! Round 6 is a little different from the others, as rather than hunt down one boss to get a key to open the door, there's four statues you need to destroy. There's two in each room, and you need to destroy them in a specific order, otherwise your bullets won't harm them. Fortunately, the manual (seriously, read the manual for this one, it's very helpful) tells you the order you have to destroy them in (even though the game won't let you shoot the statues in the wrong order) so it's not that tricky. What will be tricky is not dying, as while there's a power drink early on in the stage (see where Mary is in the left-hand screenshot? Shoot there) you'll be pestered by fliying lips and those bloody UFOs- seriously, these guys are nearly as infuriating as the Paper Card Birds from Robocod- and if you get hit while above a pit, you can forget it. With any luck, you'll have three lives by this point, so one or two drops down the pit would be OK... But no more. Anyway, let's find those statues...

First you need to destroy the one in the blue (second) room on the right side.

Second, the statue in the grey (first) room on the right side.

Third, the remaining statue in the grey room.

Finally, the last statue in the blue room, which will drop the key for you.

As for fighting these statues, you first need to shoot the base to make the head pop off. If you go to fire at the head straight away, it'll move around erratically- a bit like the butterflies in Round 4, but they're a lot faster and cover a lot more of the screen with their movement. Instead, once the head's free, keep plugging the statue with bullets- the head will stop moving as the statue fires a slow-moving flame at you. Take that time to destroy the head, and move on! You really don't want those heads to move around too much, especially near pits.

Once you're done and you've got the key, enter any door to face the final boss.

The final boss is... Some kind of giant super-computer? How did the ALIENS haul this thing here?

Whatever, let's destroy it.

First, you'll need a Jetpack to fight this boss, so foruntately the game provides you with an infinitely repsawning Jetpack to the right- grab it when you're shot. As for the boss itself, the five domes in the centre of the screen fire bullets locked onto your last position on-screen. That's a lot of bullets, and outrunning them isn't really an option. Instead, you have get level with it, pump it full of bullets and keep moving in one direction and stick at it- every couple of rounds, it'll fire just three bullets, then just one, and you should use that time to change direction and resume your attack. You're probably going to get hit at least a few times, so hopefully you've been keeping your energy as high as possible. Once you take out one of the domes, it gets a little easier as less bullets are fired, so just keep it up and once all five domes are trashed...

The computer explodes, and the colony is saved. Let's find that casket and get outta here.

Congratulations, Mary and Edger. You've brought back world peace!