I think the numbers in this game are fake, I've reloaded and taken the same 75% shot 43 times and it always misses. What gives?[
The RNG seed is saved with your game. If you reload and try the same action, you will always get the same result. This is intentional, as Jake Solomon considered 'savescumming' to make sure you hit a specific shot to be cheating. And quite frankly most people agree with him. If you want to reload because you missed 5 shots rated at 75% accuracy and then the aliens shot and killed 3 of your men in full cover then that's your business. But you will have to change history by changing your tactics.
That said, playing the game this way is not the way the game is intended to be played, and if you learn to let go of individual situations, lose soldiers, lose missions, etc, it is the finding of pretty much everyone that the game is more fun for it. Embracing the :xcom: is much better than fighting it, both for your own sanity playing this game, and the overall experience.
A Don Tacorleone came up with a beautiful quote illustrating this:
“Learning to let go should be learned before learning to get. Life should be touched, not strangled. You’ve got to relax, let it happen at times, and at others move forward with it.”
- Ray Bradbury
Can you stun Chryssalids, Cyberdiscs, or Sectopods?
No, you cannot. You also cannot stun your own soldiers who have left your control for whatever reason. If you ever have any questions on whether or not you can stun something, select a soldier carrying the Arc Thrower and mouse over the unit you want to stun. If the circle indicating the Arc Thrower's range pops up, you can stun it. If it does not, you cannot.
Speaking of stunning, how the hell does it work exactly?
Basically, to use an Arc Thrower on the enemy, you need to be within 3 squares of it. Shooting the Arc Thrower at an alien gives it a basic 'chance to hit', that it displays to you. If the Arc Thrower 'hits', the alien is disabled and that's that. There are no partial stuns or multiple hits required like we did back in UFO Defense. The 'chance to hit' is increased the lower an enemy's health is, with a very sharp hit up at 3HP. Plinking away at enemies with ballistic Pistols is a great way to weaken enemies without killing them. Later on, you can upgrade the Arc Thrower to be a little more useful above 3HP.
What does the Tutorial do?
In addition to the obvious (forcing you to move and lose almost your entire squad in the first mission), it forces you to home in North America (not a bad move) and gives you a few free buildings at your base. However, the layout of said buildings is pretty bad for the long term, so really you should turn off the Tutorial once you've got the game's basics down.
Why can't I build a Workshop or Laboratory?
You have to get an Engineer or Scientist (respectively) added to your staff via a reward. Prioritize missions that give you Engineers or Scientists.
I keep losing! It's impossible to keep up with panic! I can't respond to all these abduction missions!
Trying to keep panic down through Abduction missions is a losing proposition. The secret, however, is that Abduction missions cannot occur in a country with a satellite.
If you keep losing via panic, you are not building satellites fast enough, or you are not deploying them properly. Wait until the end of the month to get a full picture of what's going on. Occasionally you will get a panic-reducing Council mission in a country with maxed panic, which will save you from the Sophie's Choice of having too many panicking countries and too few satellites.
If you're building too few satellites, first remember that [i]you can build more than one at once![/i] Dr. Shen's Engineers are very industrious sorts that can handle incredible workloads. You can actually queue up like 50 Satellites all at once, or one at a time. Building them one at a time for later cancellation is a common way of 'ear marking' money for specific projects.
In Classic and Impossible, you may further consider that since abduction missions cannot occur in places with a satellite, you might have to prioritize covering an entire continent to keep a country from going BACK into maxed out territory with a satellite on top. Choose carefully.
Be aware that the immunity from Abduction missions only kicks in at the start of each month, so if you deploy a satellite over France on the 10th of June, it can still get an abduction mission on June 20th. You should avoid these regrettable scenarios by deploying satellites on the last few days of the month - this is the best practice for a lot of other reasons, anyway.
What do the difficulty levels change?
Most noticeably, enemy health, aim, and critical chances. Specifics vary from unit to unit. Check the X-Com wikia (url=http://xcom.wikia.com/wiki/XCOM:_Enemy_Unknown) for these specifics if you want - just check individual enemy types.
There are also more aliens on each level on higher difficulties, most noticeably on Impossible. You can generally expect to see 50% more enemies on Impossible, with relation to Classic. So on the first mission, where there would normally be 6 enemies, you can reasonably expect around 9.
On Easy and Normal, the game also 'stealth cheats' for you, as well. Every successive shot you miss will give your soldiers hidden bonuses to Aim, so if you keep plinking away at those 45% shots you will almost certainly see one hit. Aliens are less likely to hit you successively in the same manner. It's generally not a good idea to spend a lot of time on Easy/Normal for this reason, since it will give you bad habits that won't translate well to higher difficulty levels.
Also, the AI is handicapped on Easy/Normal. Basically, before moving any of its units, it has to roll a die to see if it suffers a bout of boneheadedness. This chance is small, roughly 10-15%, but the consequence of failure is making a random and extremely stupid move, such as moving a unit out in the open to be shot.
Is there any way to game the aliens so they don't upgrade?
Not really. The aliens respond to the amount of pressure humanity is throwing back at them - this is what prompts them to deploy progressively heavier and heavier assault forces. Simply by existing, you are throwing pressure back in their faces. But, that said, certain technology beelines will delay the appearance of tougher alien species by a few weeks (early armor), while others will actually accelerate it (early light plasma rifle).
That said, the progression of 'commander' aliens (Outsiders, Sectoid Commanders, Ethereals) are determined by the status of story missions, so you can make like one or two enemies easier on UFO missions by not doing the story past certain thresholds. Which is kinda cold comfort when you're fighting half a dozen angry Mutons on the way there.
Are there any cheats? I just want to blast some fool aliens!
Any time after the Tutorial ends, if you rename a soldier to one of a couple static 'hero' names, that soldier will be transformed into a nigh-immortal god of war that will absolutely demolish the shit out of any punk-ass X-Ray unlucky enough to be caught in the way. Note that if you use any of these heroes, achievements are disabled for that game.
Sid Meier - The legendary game designer and the big boss at Firaxis
Ken Levine - Another game design deity, worked on Thief, Bioshock, and System Shock 2.
Joe Kelly - I believe this is supposed to be the Joe Kelly of Deadpool and X-Men fame, but I can't be sure.
Otto Zander- Named after the X-Com commander in GuavaMoment's spine-dominatingly awesome Let's Play of UFO Defense (http://lparchive.org/X-COM-UFO-Defense/). If you're going to cheat, I recommend this one.
Chris Kluwe (PC only) - I have no idea who the fuck this is supposed to be, Google claims he's a punter for the Vikings who's a gay rights activist and plays too much World of Warcraft. Also I guess he beat an X-COM dev in the multiplayer recently or something, whatever.
I'm stuck after firing with Double Tap! I don't want to fire again!
You can just immediately end your turn (Backspace on PC).