Alien Zombie Megadeath

Easy this is not. There are 284 medals in the game, 4 for each of the 71 levels.

You'll need to really practice in order to get this trophy. There are a variety of tips and strategies that can be used depending on the type of level, mode and medal you are aiming for. Since there are so many levels which vary widely in difficulty, it's better to detail techniques and tips in general, and let you apply them as needed based on your skill and the level you are playing. Good luck!

General Gameplay
Here are some general tips and strategies that you should practice and keep in mind for all levels and modes.

• Use the D-pad to move around. The movement controls in this game can be a bit sensitive. With the analog stick, you may have the tendency to tilt it up or down slightly without knowing it and the game move your spaceman up or down accordingly, whether you wanted to or not. When you're surrounded by dozens of zombies and bullets, this is not desirable behavior. When using the D-pad, make sure to not rock your thumb back and forth too much or hold down or too much – you may move further than you intended. Press or once only when you need to move, and hold it only if you have plenty of space to maneuver in.
  
  
• Position is paramount. Where you are in relation to zombies is a huge factor in this game, otherwise you'll be quickly boxed in and it'll be game over. Know the level and learn the patterns of enemy waves – they are generally the same every time you play the level. Tailor your movement around each particular level.
  
  
• Don't fire unless you need to. You actually move slower when you are firing. So don't just fire constantly – you may need the added speed that not firing can give you.
  
  
• Never lose sight of the goal. You may want to rush across to the other side of the level to get that UFO, but unless you can safely do so, don't do it. Always focus on the particular medal you are trying to get and don't worry about things that don't affect it. So if you just need to focus on getting 10 large crystals, forget the UFOs. And don't try to get the weapon or health drops if it throws off your position.
  
  
• Effectively use jump on the top level. When you press when you're at the top of a level, you'll jump. Using this in conjunction with moving left or right allows you to jump over zombies or obstacles. You can also do this while moving backward and shooting forward – a good technique to have, particular against bats, lumpers and bullets.
  
  
• Use temporary invincibility. If you are hit by a zombie, you are invincible for a second or two. Use this to your advantage to move through zombies and obstacles and get into a better position if needed.
  
  
• Zombies react to your fire. You'll notice that when you shoot some zombies, ones above or below you might jump forward a bit in reaction. If you're quickly hopping around and firing willy nilly, you risk jumping right into a zombie in a space that was empty a moment before. Keep an eye on zombies when you fire so they don't jump into the area you're planning on going.
  
  
• Learn zombie patterns and dictate their movement. Some zombies move in a predictable way. If you are getting swamped, there are ways you get them to move which will put you at an advantage when trying to kill them. For example, Bats generally flock toward your position, but when you kill them they move away from your shots as if repelled. Many times this allows them to flank you from above or below. A good way to counteract this is to move to a level of the map with some left/right room and move towards the flock in order to get those above and below to move in that direction. Then you quickly back out and move up or down to take them out without giving up much ground. This works on Fiends as well. The more you play the game the more you'll recognize their patterns.

Maximizing Points
Many levels have medals that require you to score a specific amount. For basic Fire Fight levels where there are a set amount of enemy waves, you basically need to have perfect runs in order to meet the medal requirements. Here is what you need to do to maximize points. No level is exactly the same so you may need to experiment and tweak these strategies depending on the level.

• Boost the multiplier. This is a no-brainer. The higher your multiplier, the more points each zombie and drop is worth. You increase the multiplier by collecting crystals. Get enough crystals to fill up the meter and the multiplier increases. Note that the meter decreases over time so if you don't pick up enough crystals in time they will be wasted. There are a couple of ways to maximize crystals:
  
  
  • The large crystals that appear every once in a while definitely help to boost a multiplier, but you can get more out of them if you wait a little bit before picking them up. This is because they emit about 10 smaller crystals before they disappear entirely (perhaps 6-8 seconds). Wait until the large crystal has been around for a while before grabbing it and you'll get more value out of it.
    
    
  • Picking up the small crystals that zombies leave behind boost your multiplier even more. Kill a bunch of zombies grouped together, move in to collect crystals, back out and repeat. For zombies that appear on the far side of the screen, let them wander into the middle first so you can more easily get all the crystals after they are dead. Increase your multiplier as early as you can.
    
    
  • Make sure you get enough crystals at one time to fill the meter and increase the multiplier. It sucks to have it almost full and miss out on an increase because there aren't any zombies for a few seconds.
    
    
• Kill UFOs. Always kill a UFO if you're able to. Each UFO you kill increases its base points by 100, as long as you don't get hit. If you get hit the points per UFO reset. So if you kill your 6th UFO on a stage without getting hit, it's worth 600 points. Multiply that by your current multiplier to give the final points. So a 6th UFO with a 13 multiplier is 7800 points. When you get a long streak going, you can really start to see the point benefits.
  
  
• Kill at the right pace. On Fire Fight levels, sometimes you don't want to kill zombies too quickly, or not every UFO will appear. Choose a pace that maximizes the multiplier by grouping zombies together without forfeiting some UFOs. For Survival levels, you don't need to pace anything.
  
  
• Don't get hit. On Fire Fight levels, you get extra bonuses at the end that are increased by the multiplier. One of these bonuses is a "No Lives Lost" bonus. Getting hit and not getting that bonus could lose the medal for you. This also applies to UFOs, Defusing Bombs and Space Babies - the points per UFO/Bomb/Baby increases with each you destroy/defuse/rescue without getting hit. If you get hit, the points reset. For defusing bombs and rescuing babies, this equates to a ton of points if you can keep the streak going.