Majestic Twelve: The Space Invaders Part IV/Gameplay

Controls

 * Joystick: Use the 2-way joystick to direct the blue CG30 (or the red one if you're player 2) across the bottom of the screen; they can't wrap around.
 * Firing Button: Use this button to make the blue CG30 (or that red one if you're player 2) fire shots up at the invaders; some shall take multiple hits.
 * Special Weapon Button: Use this button to make the blue CG30 (or the red one if you're player 2) use a special weapon after gaining its powerup.
 * 1 or 2 Player Buttons: Push these buttons to begin the game as player 1 or player 2.

CG30
These two cannons are the protagonists for this game, and you must use them to destroy the invaders' formations; direct them left and right, to choose a position to fire from, then time your shots so that they arrive at the location of an invader that you are trying to hit. There are no longer any shields to protect them from enemy fire - but, when either of them collects an "A" powerup, four of them will fly into view from the left and right sides of the screen. Each hit on them from the underside will push them further into the air and any invader that touches them shall die immediately; however, they will automatically explode at the end of the current round. Getting hit by any invader's bullet will result in the loss of one "shield" (they start out with between none and three, and can earn up to eight, by collecting "S" powerups) - and, if they get hit by a bullet while they do not have any shields at all, they will explode (costing them a life). To the left is how they appear in the ground-based worlds, while below is how they appear in the air-based ones:

Regular Invaders
The main types of alien invaders still behave the same (again); they remain in formation, as they advance towards the bottom of the screen. The entire formation will either circle around as they move downwards, move to the right or left until the far column reaches the side of the screen then drop down and move back towards the other side of the screen, or move downwards - and the lowest invader of every column shall fire bullets down to the ground (and you will receive 10 extra points for every one you block, or for the bullets that cannot be blocked, attempt to). If any one invader manages to reach the bottom of the screen, both CG30 will die immediately (regardless of how many shields they have remaining), as opposed to immediate game-overs.

UFOs
As in the four previous titles, UFOs appear randomly, over the formation; they will appear on one side of the screen, and cross over to the opposite side. During this time you can attempt to shoot them for bonus points - and the point value that is awarded once again appears to be random, but now ranges up from 50 to 6400. They'll also leave powerups behind that fall down to the bottom of the screen and bestow their effects on both CG30 when collected.

Cattle
After your chosen first, third and fourth worlds (Rounds 7, 32 and 41 in the US version), there shall be a "Cattle Mutilation" bonus stage; six Cattle (shown in the image to the left) will appear below the two CG30s, and several UFOs (shown in the image to the right) will fly into view, from the left side, top, and right side of the screen, which you must attempt to destroy for bonus points (the flashing indicator upon the right side of the screen shows how much you have received when you shoot one). Occasionally, one of the UFOs will fly down to the CG30s' level and beam up one of the Cattle, as the text "HELP" appears on the screen, and it starts flying up towards the top of it - and if you shoot the offending UFO down, the text "THANK YOU" will appear upon the screen as the Cattle slowly falls back down to the ground (but if you should shoot the Cattle itself and kill it, the text "OUCH" will appear on the screen as it MOOs from the Yamaha YM-2610). At the end of the stage, you will receive 5000 points for every Cattle you have (if you still have all six of them, you will receive an additional "PERFECT" bonus of 20000 points), along with the points for every UFO you killed; however, if the UFOs beam up all six Cattle (or you accidentally kill them all) before the stage is over, it shall immediately end.

Circling Invaders
These secondary types of alien invaders will circle around in a clockwise (or anticlockwise) direction as they descend towards the bottom of the screen.

Special Invaders
These types of alien invaders are exclusive to certain areas (or rounds in the US version), and one type makes up the entirety of one row of a formation.

Worlds 2A-4 and 4A-4 (US: Rounds 11 and 36)
This boss invader attacks by firing lasers down at the two CG30s from its four tentacles; the eye is its only vulnerable point, and it is worth 50000 points.

World 2B-4 (US: Round 15)
This boss invader attacks by firing missiles down at the two CG30s from its sides, and dropping its bottom part to fire two "double-helix" lasers down at them (before it returns to it, like a boomerang); as it reveals its face at this point, this is the only time it is vulnerable, and it is again worth 50000 points.

Worlds 2C-4 and 4B-4 (US: Rounds 19 and 40)
This boss invader attacks by firing missiles down at the two CG30s from its sides, and dropping its eye (which is actually a shuriken) before it returns to it like a boomerang (or the bottom part of the previous boss invader); this shuriken is its only vulnerable point, and it is, once again, worth 50000 points.

World 5-4 (US: Round 45)
This boss invader attacks by punching down at the two CG30s, while firing lasers at them from its arms; it will also occasionally open its mouth and fire laser beams down at them. The arms can be destroyed (but are not worth any points), so you should focus on the body - and it is worth 100000 points.