- Don't play the original version. Use OpenX-Com, found at http://www.openxcom.com/ It is made by goon SupSuper and fixes may bugs and limitations of the original game and also has many additional options that range from quality of life, to screen resolutions, to minor tweaks to actual gameplay mechanics.
Before Your First Mission
- The best starting places for your first base is America or Europe. The surrounding countries contribute a large amount of money to your cause every month.
- When you begin your game, begin building more Living Quarters and General Stores. You'll need them for more staff and the general accumulation of items you'll generate after missions.
- Change both Interceptors' weaponry so they use Avalanche Missiles; these are longer range than most UFO beams and should take out all UFOs until you can get Plasma Beams.
On The Ground
- You can right click to have a unit turn and look. The Skyranger has windows allowing you to see a good portion of the map simply by right clicking. Otherwise, don't get out of the ship on the first turn. Aliens often start with full TU and facing the ship. Wait for them to waste a turn moving instead of handing them your team on a silver platter.
- Understand that units are expendable; it is not uncommon to have 50% mortality rates for new players. More experienced units (especially Psi Ops) are less expendable, but you can always hire more Rookies.
- Auto shot always pays off statistically, but consider aimed shots when you really don't want to miss wide, like when shooting with other soldiers in front of the shooter or firing explosive weapons.
- Use the "reserve TUs" buttons to make sure your guys have some TUs left for reaction fire, and never just send one person out on their own. They'll get killed and you won't be able to see the enemy that killed them. Try to send out scouts with people with high accuracy covering them.
- Electroflares are reusable, but aliens can still see better in the dark than you can.
- You don't lose points for environment destruction. Grenades and rockets are cheap. If you want a shortcut, make one. Not sure if a house has an alien in it? Blow it the hell up. It's a lot quicker and safer than playing X-SWAT: Sweep and Clear.
- Exception: Don't throw grenades around alien tech, destroying it means you can't salvage it.
- Try to capture a Navigator of any race ASAP, this unlocks the Hyperwave Decoder. Hyperwave is your immediate priority once you can research/build it. Sectoid Leaders are also high value targets and worth losing a few men for.
- Terror missions are hard in the early game. If you think you cannot handle a terror mission, go there anyway and abort the mission on the first turn. Though you'll receive a bad score, the penalty for allowing a terror mission to go unchecked is roughly 3 to 4 times worse. (This is especially true of Snakemen Terror Missions.)
- Tanks are great scouts, they have 100 TUs and real armor. Great early game stuff. Soldiers can hide behind them too. Rocket tanks can kill stuff to by virtue of rockets.
Between Missions
- Your primary objective is shooting down and recovering UFOs. This is both how you get the most money, and how you keep yourself in the council's good graces.
- Remember that anything you physically destroy during battle (like UFO parts) is stuff you won't get to research/sell though, so go easy on the explosives inside the UFO.
- Build an Alien Containment facility ASAP. A lot of the tech tree is trapped behind capturing aliens alive. (A rush of rookies with stun rods are your likely first source for these.)
- Remember that when you hire a soldier/scientist/engineer, this is not a one-time payment, but the cost PER MONTH. Plan accordingly.
- You can rename soldiers, which makes it easier to remember who's good at and equipped for what. Try not to give anything heavy to someone with low Energy, and never give an AoE weapon to someone with a weak Psi Defense.
- Never, ever, EVER sell Elerium-115. This is the catalyst for everything alien tech; from fuel for advanced planes to making ammo for plasma guns. You cannot manufacture it, it must be captured from aliens.
- Try to research Laser Rifles as soon as possible. Other laser weapons aren't really worth it, but Laser Rifles will be your bread and butter for a long time, until you get reliable access to Heavy Plasma Guns. Both are two-handed weapons, so keep your other hand open when using them.
- Personal Armor is great and important, get lots of it, but don't expect it to do too much. It will cut down on the one-hit-kill mortality rate of your soldiers, but it will not prevent it.
- There is never a reason to have scientists and engineers running idle. Each Lab can hold 50 Scientists. A given Workshop can only hold 50 Engineers, but whatever they're building takes up space too. Be aware you may need multiple workshops if you want to build something big like an aircraft.
- If a base is attacked and you have no soldiers present, it's an automatic loss. Tanks cannot defend a base on their own. Even your research/manufacturing bases should have some rookies with laser rifles and some tanks to defend it. Aliens 'forget' the location of your base after an assault, which can buy you the time you need to build some air defenses.
- Save at least one of each thing you find to research, never sell the last unit of some item unless you've researched it first.
- If there's a suspicious uptick of UFO activity in a certain area it may be an alien base, send a Skyranger (longer loiter time than fighters) to patrol that point (one fuel tank of patrolling is plenty of time to reveal the base if there is one).