XCOM: Enemy Unknown

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.

Take one of the survivors from the first mission into every battle until the game gas been completed. Consider using the sniper, as it usually operates from a distance and is safer than the other classes. Also do this in easy mode on the basic game (Enemy Unknown). Make sure your select soldier almost never gets hurt. If a new mission starts and your soldier is still injured, skip the mission.

Each of the following alien autopsies must be completed during the same playthrough. Note: Have a starting base at South America to get autopsies that are completed instantly.

Sectoid

Sectoid Comander

Sectopod

Thin Man

Muton

Muton Berserker

Muton Elite

Floater

Heavy Floater

Drone

Cyberdisk

Chryssalid

Ethereal

Do not attempt this in the default game. It must be done in Enemy Within.

Have one of your soldiers wearing Archangel Armor. The soldier must kill an enemy while flying. Archangel armor is an expensive late game armor that must be researched first. It helps the wearer to fly. Wearing Archangel Armor on a Sniper class soldier with Squadsight ability is the easiest way to earn ""Angel of Death".

Take out the Exalt base. It can be found at where "Where in the World" is earned.

Play under the easy difficulty setting. Note: Sneak and save the civilians you can reach; the enemy will kill less civilians if do not know you are present. Have six of your best soldiers equipped with ghost armor and armed with the best weapons. Have at least two assault (for close combat) and sniper class (for when civilians are among the enemies). Do not lose any of your soldiers and no more than four civilians during the mission. Try to kill all enemies quickly to win the mission without having to save all the civilians by getting near to them.

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.

Build Psionic Labs and test your soldiers for Psi-Abilities. This requires "Interrogate Sectoid Commander" or "Sectoid Commander Autopsy". Kill or capture the Sectoid with the larger head. With the second wave option "The greater good", you must interrogate the alien. The chance of getting a Psi soldier depends on his Will. The first soldier will have a bonus to that stat. The "Iron Will" upgrade will help get a high amount of Will on your soldiers.

Complete the 53 research projects in the base game. Note: Most are available during normal game progression. However the nine different interrogations are dependent on the live capture of the relevant aliens using arc throwers. Also the "Guided fusion launcher" and "Fusion lance" research projects will only become available after you get a fusion core, which are only acquired in missions involving an alien battleship, usually during month six of the campaign.

• Alien materials
• Alien nav computer
• Alloy cannon
• Arc thrower
• Archangel armor
• Beam weapons
• Berserker autopsy
• Carapace armor
• Chryssalid autopsy
• Drone autopsy
• Elerium
• EMP cannon
• Ethereal autopsy
• Ethereal device
• Experimental device
• Experimental warfare
• Floater autopsy
• Fusion lance
• Ghost armor
• Guider fusion launcher
• Heavy floater autopsy
• Heavy lasers
• Heavy plasma
• Hyperwave communication
• Interrogate berserker
• Interrogate ethereal
• Interrogate floater
• Interrogate heavy floater
• Interrogate muton
• Interrogate muton elite
• Interrogate sectoid
• Interrogate sectoid commander
• Interrogate thin man
• Light plasma rifle
• Muton autopsy
• Muton elite autopsy
• New fighter craft
• Outsider shard
• Plasma cannon
• Plasma pistol
• Plasma rifle
• Plasma sniper
• Precision lasers
• Psi armor
• Sectoid autopsy
• Sectoid commander autopsy
• Sectopod autopsy
• Skeleton suit
• Thin man autopsy
• Titan armor
• UFO power source
• Weapon fragments
• Xeno-biology