While Ratalaika Games can occasionally release a game that's a challenge to complete, this week's offering is not one of those. Their latest release, Zeroptian Invasion, once again allows players to earn 1000 Gamerscore in around 10 minutes, and we've put a quick guide together to tell you how to do it. The game is normally available to purchase for the price of US$4.99/£4.99/€4.99 but is currently on sale at 20% off.Zeroptian InvasionZeroptian Invasion is this decade’s answer to the arcade shooters of yesteryear.Set price alertBuy The Space Invaders-esque title tasks players with shooting Zeroptian aliens out of the sky and prevent them from invading the F-1 system planet. The waves of aliens get quicker as they approach the bottom, and when you whittle down their numbers to just the last alien standing, he speeds up again. Players begin the game with two lives, and a life is lost every time you get hit by an alien missile. After each boss is defeated, players will get a checkpoint, and if all lives are lost, players begin again from the last checkpoint. To earn the full Gamerscore, players will need to complete seven short levels, defeating the two bosses along the way.Level 1The first level sees players face a wave of 16 aliens in three tiers. Three barriers are placed at the bottom of the screen to protect you from incoming missiles, but a little bit of these is destroyed with each hit until they completely disintegrate. Occasionally a UFO will fly across the top of the screen. Shooting this will produce a power up that players must catch as it drops to the bottom of the screen. If you really want to get the achievement out of the way, you can be hit by a missile to die for the first time too, although there's every chance you'll be hit at least once as you progress anyway. By shooting the aliens to accumulate 1000 points, catching your first power up, and being hit by a missile, you'll get three achievements:The Boosted achievement in Zeroptian Invasion worth 80 pointsGet a power upThe Don't give up achievement in Zeroptian Invasion worth 80 pointsGet 1000 scoreThe Welcome achievement in Zeroptian Invasion worth 80 pointsDie for the first timeLevel 2The second level sees players face a wave of 20 aliens in four tiers. Two barriers are placed at the bottom of the screen to protect you from incoming missiles. As your score accumulates between levels, shooting all of the aliens in this level will mean you hit a total of 2,000 points and will earn another achievement:The Good job achievement in Zeroptian Invasion worth 80 pointsGet 2000 scoreLevel 3The third level sees players face a wave of 21 aliens in four tiers. Just one barrier is placed at the bottom of the screen to protect you from incoming missiles and this doesn't get destroyed. This is because once all of the aliens are killed, the barrier starts flying around the screen. It turns out it's actually the game's first boss. He'll drop two types of projectiles towards you but both fall slowly and are easy to avoid. His health is displayed in a meter at the bottom of the screen. Once his health is depleted, you'll get an end of section bonus to your score. The bonus is based entirely on hit accuracy, but should still be enough to push your points total above 10,000. This means you'll get four achievements by the time you finish the level:The Well done achievement in Zeroptian Invasion worth 81 pointsGet 5000 scoreThe A hidden enemy achievement in Zeroptian Invasion worth 83 pointsDestroy the boss of the first areaThe That will teach them achievement in Zeroptian Invasion worth 84 pointsGet 10000 scoreThe Going forward achievement in Zeroptian Invasion worth 83 pointsComplete 3 levelsLevel R2At the end of the third level, you'll fly through a red portal and be transported to this level. The enemies take a different approach in this level, instead zig-zagging across the screen in small groups. You don't have to shoot the aliens, just merely avoid them and their missiles. As you don't need the points, the easiest thing is to just let them fly off the bottom of the screen so you can quickly progress to the next level. You won't get any more achievements in this level.Level 4Here, the enemies return back to a Space Invaders-esque pattern. This level sees players face a wave of 20 aliens in four tiers, including spiders that throw webs. Zig-zagging shooting stars fall from the sky along the edges of the playable area. Two barriers move side to side across the screen to protect you from incoming missiles. The aliens in the top row that have the long arms will take two hits to be defeated. Once the aliens have been defeated, this will be your fifth completed level for another achievement:The Excellent achievement in Zeroptian Invasion worth 85 pointsComplete 5 levelsLevel 5This level sees players face a wave of 18 aliens in four tiers. Large asteroids fall from the sky in the centre of the screen, and there's just one moving barrier to protect you from incoming missiles. The safest thing to do during this stage is to stay on the edges of the playable area and pick off the aliens from each side. During this level, you should hit a total of 15,000 points which means you will earn another life. Once all of the aliens are defeated, you'll progress onwards but you won't get any more achievements in this level.Level 6This is the final level you'll need to complete. This level sees players face a wave of 16 aliens in four tiers as the crawl around a spider web. There are no barriers to protect you now. Once all of the aliens have been defeated, three exclamation marks at the bottom of the screen mark where the game's second boss will appear, so make sure you're clear of those. The second boss is a giant insect that shoots ordinary missiles and bouncing red bubbles. While the bubbles don't disappear out of the playable area on their own, then can be shot and destroyed that way. Like the first boss, his health is displayed in a meter at the bottom of the screen. Once his health is depleted, you'll finish the level and see the end of section bonus score screen. At this point, you'll get the final two achievements:The A messy enemy achievement in Zeroptian Invasion worth 94 pointsDestroy the boss of the second areaThe Impressive achievement in Zeroptian Invasion worth 235 pointsComplete 7 levelsCongratulations on another quick completion!We've got the full list of Zeroptian Invasion achievements - check the list for guides to unlocking them.Check out our Best Xbox Shoot 'em Up Games Available in 2018 article for a compilation of other great games in this genre.