Take note of your starting location or keep a saved game file at the global map each time you are almost finished with a game in order to keep track of which locations you have already completed. Play under the easy difficulty setting and use second wave options. Because this must be done within the same game, either Enemy Unknown, or Enemy Within, select the one you have more completions with. If you choose Enemy Unknown, you can flank and overwatch an enemy and they will remain stationary (unless one of your soldiers is also flanked, in which case they will get shot). This cannot be done in Enemy Within. Use the Slingshot pack to get an advantage early on by capturing a live Muton and studying plasma weapons to get research credit for them. Additionally when you complete the final mission you can make the Blaster Launcher if you have enough fragments. The best method to get superhuman soldiers is to use the second wave option "Not Made Equal". Have the "Instantly promote to squaddie" and "Iron will" upgrades and hire at least seventy soldiers. Examine them and only upgrade those whose Aim is at least 80 and Will is at least 50 (60 recommended). Use them to build a squad that hits often and can mind control an enemy frequently. It is also possible to use the psycho test to get all "gifted" troops. Place three men into the test chambers, save the game, allow the test to complete, note the names of the ones that are gifted, reload the saved game, remove the non-gifted men, and repeat until you find three gifted soldiers. You can them spend some time upgrading them to max Psi level.
Easy "Bait the Hook" trophy
This requires "The Slingshot Content Pack". If Zhang has been part of anything completed, this achievement will be available. This is a Unique Council mission that is part of the DLC, and can be done under any difficulty setting. When selecting a squad, consider that the follow-up mission aboard the alien battleship will start after Confounding Light's completion and not allow time for wounded soldiers to recover. The mission has a ten turn time limit. Activating transponders will not extend the time limit. Your squad must advance quickly enough to place all four transponders and reach the train's control console within that time limit. Reaching the control console with your last action in the last turn will still be a failure. Eliminating all opposition is not required to complete the mission. Aliens who are not an immediate threat should usually be ignored to focus on the transponders. Only one soldier needs to reach the train's controls. A Sniper with Damn Good Ground and Low Profile can hang back and take advantage of high ground and low cover by climbing the ladder at the rear of the train, then advancing slowly along the roof. An Assault with Lightning Reflexes can be used to counter the aliens' frequent Overwatch use. If possible, consider replacing a Sniper or Heavy with a second Assault, as Run & Gun may also be useful. A Support with the Sprinter ability may be also do well. Keep a Heavy with a rocket in reserve to clear the control room quickly; a pair of Thin Men occasionally will be holed up inside. Damaging the train during the mission is allowable.
Easy "Lone Wolf" trophy
Progress until near the end of the game under the Classic difficulty setting. Note: You will need to save and reload the game frequently. Use a sniper in a flying suit, preferably with Psionic abilities and the Double Tap ability. Equip him with a plasma rifle and wait for the small alien craft to appear. Shoot it down so some aliens will die and save some time. At the start of the mission, fly up with the jetpack and move towards the alien craft. The Double Tap ability will help you to kill two enemies in one turn, and the flying suit will help kill them from a distance. However an Etherals can mind control you. Frequently saving and reloading will solve this issue. Select the Classic difficulty setting. If available, use the "Second Wave" option "Save Scum" to allow new seeds if you get a bad outcome. Develop and build the Hyper Wave Relay and have Colonels. The Hyper Wave Relay lets you know exactly what will be encountered at a crash site, and thus avoiding getting surprised by Etherals. Do this against a Small Scout, which typically has between five to twelve aliens on board. Foundry should also have been built. Play as a Heavy with Ammo Conservation to minimize reloads and Deep Pockets to carry extra grenades. Also set up with Bullet Swarm (shoot twice), Shredder Rocket (extra rocket), Rapid Reaction (second shot on Overwatch after a hit), Grenadier (with Alien Grenades), Rocketeer (additional normal rocket). Equipment should include Heavy Plasma, Blaster Launcher, and Titan Armor. If playing with Enemy Within, also consider Neural Dampening, Hyper Reactive Pupils, and Forget the Meld.
Easy "Pain in the Neck" trophy
Successfully stun an Exalt-Agent with the Arc-Thrower. Do this by shooting the agent down to less than 3 points of health, then move close to him and use the Arc-Thrower.
Easy "Taking A Load Off" trophy
Note: This requires Enemy Within. The "Seeker" robotic flying squid has a strangling attack. Kill a Seeker strangling your squad member it kills them.
Engineers
Try to have a ratio of 70% engineers to 30% scientists for best results, as well as . the Workshops to support them.
Evil Crysalid terrorists mission
When on a Terror mission that has evil Crysalid terrorists, you do not need to kill the Zombie Civilians to finish the mission. As long as all Alien forces have been defeated the mission will end successfully.
Have UFOs appear in a different country
If a UFO is spotted in a country that you do not have much for defenses or you want to lower panic somewhere else (by completing the mission to clear it), reload a previous saved game. It should still come up, but will usually be in a different location. You can continue to reload until it is in the country you desire.
Heroes
Go to the Barracks and select "View Soldiers". Select a soldier, then select "Customize". Note: This can also be done from the "Customize" menu at the "Deploy" screen. Change the name of the soldier to one of the following entries to unlock the corresponding character. Note: This will prevent achievements or trophies from being earned.
Hero
Name
Joe Kelly (Heavy)
Joe Kelly.
Ken Levine (Sniper)
Ken Levine.
Otto Zander (Assault)
Otto Zander.
Sid Meier (Support)
Sid Meier.
Panic levels
Keep Panic under control to avoid losing countries. Building satellites is one way to do this. However, choose your missions carefully and select those where the panic reduction is most needed.
Proximity bonuses
Plan ahead when building new rooms to keep the costs within reason. Having rooms of the same type next to the other usually gives you various proximity bonuses.
Re-attempting missions
If you are having problems and fail a mission, reload the auto save from the Geoscape. Select the same mission and restart. You will begin the mission with a new random map and enemy placements. This can be useful when you are out-numbered and out-gunned.
Satellites
Build satellites as soon as you can and continue to do so. They give you money monthly, and reduce panic levels. If you can fill a continent, you will get extra bonuses. The easiest continent to start with is South America.
