X-COM: UFO Defense - Walkthrough

Early in the game, the aliens send scout ships to Earth. All these ships are classfied as small or very small. This means that they are easy for your interceptors to shoot down. An interceptor armed with either stingray or avalanche missiles can take down a scout vessel without being damaged. An interceptor armed with only a cannon will take down a small UFO, but may suffer light damage. Being damaged means that it will have to be repaired before its next mission. To shoot down these UFOs use the standard or cautious attack. An agressive attack may take your interceptor within range of the aliens' weapons. To shoot down larger UFOs requires better weaponry. An interceptor with two avalanche missile launchers has a chance to take down a medium on standard or cautious attack. It may run out of missiles. An interceptor armed with at least one plasma beam can shoot down a medium or large. To take down a very large UFO, you need even better technology.

If a UFO is shot down over land, it may form a crash site. If a UFO is shot down over a body of water, the UFO cannot be recovered. Once there is a crash site, you need to send troops to investigate that crash. They need to use a Skyranger transport craft to get there. Load up your Skyranger with the most advanced weapons and give your troops the best armour you have available. They will need it. Land during the day time. The aliens see just as well during the day as at night. Your troops, however, do not. In the battlescape, the aliens have the advantage. The aliens are hiding throughout the battlescape. This includes any buildings and inside their UFO. Use cover to your advantage. When deploying out of the Skyranger, use the wheels and unloading ramp as cover. If possible, even use a smoke grenade. Try to have your troops behind some cover when it is the aliens' turn. Ducking is also good. This makes your troops harder to hit. When shooting at the aliens, try to use an auto shot. Pistols do not have this option. The auto shot gives you three shots for the time units of only a little more than a single snap shot. An aimed shot is very accurate, but takes up almost all of your time units. A snap shot is the cheapest type of shot time unit wise, but not as economical as an auto shot. Use the snap shot only when you do not have enough time units for an auto, or you need to conserve your ammunition. Conserving time units can also be good. If a troops with time units left over from the previous turn sees an alien, he or she may react and shoot during the aliens' turn. Using flanking tactics is very effective against the aliens. If you can sneak up on an alien from behind, you can take an auto shot at point blank range. This is the best tactic against the well armoured aliens. Using snipers is another effective tactic. Put a man upstairs in a buiding. When an alien is seen by another troop, even though the sniper cannot see the alien, he can still shoot. Load your weapons, and good luck!