Return of the Invaders/Walkthrough

Circling formation
This type of formation first appears upon the introductory stage; the first and third rings of invaders (the former of which will always be comprised of Zicon) will fly around in an anticlockwise direction, while the second ring will fly around in a clockwise direction as they descend towards the bottom of the screen and fire bullets down at the Xerovy (the red ones can be blocked by its shots, but the blue ones cannot). You must fire upwards between (or through) the "Xero-Guards" to kill the invaders - and if you wing a Flector, it will fly up into the air and fall down towards the bottom of the screen. If you manage to shoot it before it falls off the bottom of the screen, you will receive 400-1600 points (depending on how close it was to you); however, if it lands on the Xerovy, it will kill it. The four Xero-Guards will absorb both your and the invaders' shots - and, you can once again create a hole in one of them to fire up through, but the invaders' bullets may drop through the hole as well. As you kill more and more invaders, the remaining ones in the formation shall speed up and the last remaining invader will move the fastest; however, if three or more Zicon remain at the end of any stage, it will invoke a Challenging Stage, as they fly up to the top of the screen and transform into one of three types of Mother Ships. They shall then fly around above you while sending out eight types of Bonus Invaders flying down towards you.

Horizontally-moving formation
This type of formation first appears on the second stage; it was the one employed by the invaders of the three previous titles, and the invaders (the top row of which will always be comprised of Zicon), will move to the right, drop down once the far column has reached the side of the screen then move back to the left. To prevent those invaders from dropping down sooner, you should concentrate on the ones positioned in either column edge - and if you should wing a Legard, it will deflect your shot, then send it flying back down towards you (which can kill you if you do not move out of the way in time). Starting from the 2nd stage onwards, UFOs will randomly appear above the formation which you can try to hit for bonus points; they will occasionally be carrying powerups (the blue "Gazel", the yellow "Goral" and the red "Gowl"), and if you do not hit them dead-centre, the powerups will fall down onto the Xerovy and bestow their effects upon it for the remainder of its current life. It is also worth noting that when you do kill a Legard (by shooting it dead-centre), it will leave one of four "Mystery Invaders" behind (which are worth between 400 and 10000 points when killed) - however, if any of the first three types fly into the Xerovy (the fourth type, which looks like Mario, shall never do this) they will kill it.

Vertically-moving formation
This type of formation first appears on the fourth stage; the invaders (the top row of which will always be comprised of Zicon), will all move vertically, towards the bottom of the screen. Starting from the previous stage onwards, the "Xero-Guards" will also have occasionally started moving, to try and block your shots - so you should destroy them yourself, to prevent your shots from getting blocked (if the invaders touch them they shall automatically explode). If any invader manages to reach the bottom of the screen in any of the types of formation, the Xerovy will automatically explode and a sombre tune will start to be heard from the two Texas Instruments SN-76496s as the screen begins flashing several different colours; the text of "XEROVY DESTROYED" will then appear on the screen, and the text "PLAYER X GAME OVER" (X being 1 or 2) shall appear above it (due to the fact that the Xerovy will receive an extra life at 30000 points, 80000 points, and every 80000 points thereafter by default, this is the most common cause of game over). If you had scored over 20000 points, the text "CONGRATULATIONS! ENTER INITIALS" will appear on the screen as the "high score" theme starts to be heard - and once you have entered your initials the game will return back into attract mode.