Scenarios include counteracting alien abduction attempts, searching crashed UFOs, rescuing civilians, and assaulting various ET installations. Items recovered during the tactics sections fuel scientific research in the simulation mode, and technological breakthroughs in the strategic section enhance the abilities of squad members during the tactical portions of the game.
You will always need aircraft, and since North America has only three member countries on The Council you can reap the benefit of reduced Interceptor costs fairly early. XCOM’s first two missions and initial base simulation section are available as part of an interactive tutorial.
When a Rookie gains enough experience to advance to Squad die rank, he or she is randomly assigned a specialty role. Squads include only four or five soldiers for the first few missions, and your slowly developing array of specialties will sometimes limit what classes you can bring to the table.
Early in the game you may want to use a number of Rookies on single missions, allowing them to advance to Squad die and unlocking their hidden specialty. All are useful, especially in conjunction with other classes where individual weaknesses can be covered by the abilities of squad mates.
Most six-man squads should contain at least one member of each specialty, and fill out the other two personnel slots according to player preference and mission parameters. Their combination of high mobility and powerful close-range attacks suits them well to UFO Crash infiltration and alien base assaults.
They also make superb scouts on the open battlefield, stepping into the fog of war while their squad mates wait just behind on Overwatch and Reaction Shots, triggering enemy movement and allowing the team to make reaction shots. Equipping a Rifle rather than a Shotgun increases their range but blunts their damage potential.
Second, Assault characters can get into a lot of trouble if even slightly mismanaged, finding themselves surrounded and overwhelmed by ambushes. It is absolutely essential that Assault troops never move into unknown territory without the benefit of protective fire, with squad mates in range and on Overwatch or ready to respond.
Heavy specialists carry powerful automatic weapons and explosive rocket launchers. Their talents lie in their ability (after developing Bullet Storm) to fire twice on turns where they make no movement, in their affinity for area effect attacks, and in their unique suppression abilities, which force enemies to keep their heads down during the Alien phase or risk powerful automatic counter-attacks.
Their powerful Headshot ability strongly increases their chance of a critical hit. A properly placed Sniper can dominate a battlefield, dealing lethal damage to targets softened up, pinned down, and flushed out by other team members.
Support personnel are battlefield medics and area control troops par excellence. Their smoke grenades are absolute lifesavers when the player makes a mistake that leaves a soldier vulnerable, and their Medici affinities allow them to heal far more effectively than other classes.
They can develop good mobility and suppression capabilities and provide buffs to other troops. While they devote part of their time to protecting and healing other squad members, they are deadly combatants.
Once you have a core squad of six reliable soldiers, you should occasionally rotate rookies into your less-difficult missions. Having a stable full of classed Squad dies may come in handy later in the game when wounds become a greater factor.
Late in the game, some of your soldiers will gain access to special PSI Abilities. While you won't have to worry about this for some time, you may want to read up on it in the Psi Abilities section of the Wiki.
You may also want to build a Workshop early on, as you’ll need more workers than your starting corps of Engineers for almost every worthwhile bit of construction. This will give you enough Engineers and Power to create your most important Base improvement: Satellite Uplinks.
Without enough Satellite coverage, aliens run amok, panic levels rise, nations leave the Council, and income decreases. Conversely, a well-developed satellite network adds monthly income for every covered nation, special bonuses for every completely covered continent, and early warning of alien incursions, allowing you to intercept UFOs and lower panic levels.
Note that building an Uplink doesn’t actually grant you any Satellites, just the means to control them. Laboratories, Workshops and Satellite Uplinks all gain proximity bonuses for adjacent placement.
In the long run it can be more efficient to dig down a level when building other types of Facilities, saving topside space next to synergistic areas. Start plotting your route to the nearest steam, as you'll want to build a Thermos Generators soon as you can.
Your early-game armament is fine against Seconds and Thin Men, but mid-to-late game enemies are much more heavily armed and armored. This Tier-II suit is light years ahead of your basic body armor and will increase survivability of your forces.
The default COM interceptors are woefully unequipped to handle medium and large UFOs. You should always give Research projects marked “Priority” a quick look, as they are integral to advancing the plot.
The benefits of a fifth squad mate present on the battlefield outweigh even the greatest weapons technology advances. With quicker recovery you need fewer troops to fill in holes made by wounded warriors.
Different countries offer different rewards for intervention, either cash, scientists, engineers, or experienced soldiers. Early in the game the number of available engineers can be quite constrictive on your Facilities development and your need to build satellite coverage.
Despite being a game about Extra-Terrestrial invasion, psionic powers and inter-dimensional travel, COM treats violence with a degree of realism. The AI fights with remarkable intelligence, utilizing teamwork, terrain, and covering fire.
Alien Weapons are often superior to your own, and the ET's have the added bonuses of flight, psychic powers, and Chrysalis giant-zombie-breeding-carnivorous-poisonous-purple bugs. In the elation of defeating a powerful group of foes or in the desire to just end the tension and get on with things, even a canny Commander will occasionally slip up and overextend a scout's Dashing maneuver just a little to far, or position a sniper where he doesn't have quite the line of fire you thought he would.
If you've played other Tactical simulations set in fantasy worlds you may not be prepared for just how vital cover is in COM. Put simple, soldiers caught in the open by alien plasma weapons are as good as dead.
Speaking of Overwatch, it's important for new players to understand the concept of Reaction Fire. Alien Units also benefit from an interrupt move during your turn when you first discover them in the fog of war.
Overwatch is a combat maneuver which allows your units to act during the Alien turn. By first placing your Snipers, riflemen and Heavies on Overwatch, you can sometimes use Assault troops to half-move forward and lure startled foes into a preemptive attack.
This bait and hook tactic is absolute murder in conjunction with the Sniper's Squad sight ability. Nothing gets a soldier killed more quickly than walking around a corner into the guns of an enemy fire team.
COM enforces a fog of war perspective, which means that you can only see what is within your soldier's line of sight. The interiors of rooms, areas beyond a certain distance, and even the other side of a closed door can all conceal lethal ambushes.
You can freely switch back and forth between your troops with the mouse controls or TAB key. In tight spaces, scout cautiously and always move your point man before your heavies.
Your soldiers carry an unlimited number of clips for all firearms and energy weapons, but you must expend a turn-ending half move to exchange magazines. Nothing puts a damper on a soldier's day like bracing their weapon against a Berserker charge and discovering they have no bullets left in their broomstick.
Unless you're in a terrible hurry, (such as rushing ahead to disarm a bomb), take time after every firefight to reload. Also note that some weapons like grenades and rocket launchers can't be reloaded during a mission.
Misses with energy weapons or blasts from rockets will knock holes in walls, sometimes revealing other rooms and alerting the enemies lurking behind them. It's also possible to use an explosive to deliberately destroy the cover an enemy is sheltering behind, opening him to subsequent attack by a squad mate.
Soldiers at higher elevations enjoy Aim and defense bonuses against foes positioned beneath them. A simple roll of the mouse wheel will often reveal elevated perches perfect for extending your vision or ideal for a sniper's nest.
The last thing you want to do when going after a live specimen is to charge into the middle of an enemy formation with a stun gun. Before any mission where you anticipate a chance of catching a live alien, give the Arc Thrower to your Assault specialist.
When you have engaged two or three groups of foes and sense you are nearing the end of the mission, select a single alien as a designated survivor. Stop using Overwatch (so that you won't accidentally kill him) and eliminate his squad mates.
Then move your Assault trooper to within range of the alien, hunkering down on your approach. If too many soldiers are killed or wounded at once your squad may be unable to effectively respond to incursion.
These troops will be much less powerful than your veterans and have no Class specialty, but you can train them by bringing one or two along on easier missions to build their experience. If your fighter fails to down the target UFO before time expires, the alien craft escapes.
Your default fighter weapons are quite weak, only effective against small and some medium UFOs. Laser Cannons are useful, but when deployed on standard Interceptors they should be paired with Defense Matrices as they require the fighter to close with the Alien craft before attacking.
They are very important in the early game when your fighters are weak and under-armed, and prove essential when trying to bring down the Overseer spacecraft using conventional aircraft. Second, even after Research many of these items (even the bodies) become important components in building high-tech Facilities and equipment.
Finally, countries will periodically make cash or personnel reward offers for these items at prices much higher than the Grey Market allows. Until you become familiar with the flow of the game, it is advisable to follow a rule of thumb dictating that no more than 1/3 of any corpse should ever be sold on the Gray Market, nor more than 1/5 of available common stock like Weapon Fragments.
Some items including miscellaneous UFO pieces and damaged equipment are clearly designated as unsearchable when clicked on in the Gray Market. Every country with Satellite coverage commits regular monthly funding to COM.
Every country that leaves The Council takes monthly funding with it, and the budgetary balance of your Facility is precarious. Even a single escaped Alien ship can cost you a full letter grade and a degree of support.