Some sorta FPS RPG hybrid with moral decisions, weapon upgrades, massive battles and smaller commandoish missions, a cover system, loot hunting, ammo scavenging, lots of side missions, a strange alien world full of weird creatures and abnormalities, exotic weapons and vehicles, lots of unique and even random encounters.
In my dream game everything lives off death, traders got all their guns from dead people, technicians may have tools reverse engineered from items taken from killed enemies.
So your in a big war zone with a couple factions trying to kill each other over this unique, wonderful and terrifying world your in.
I could go on about my dream game all day, but i do wanna say that in Mass Effect while there are moral choices to some extent there is rarely a unique upside or downside, or result of that action somewhere down the line.
Its almost always just intimidating someone to lower their prices, or sweet talking them to make a discount, all that is different is dialogue.
In my dream game moral choices have upsides and downsides and affect the game later on in some way.
You may find a dying friendly soldier who needs immediate medical attention, you can try and find a medic to send his way, (too little too late, he will already be dead) simply take all his ammo and leave him there, or drag him war hero style through a bloody battlefield to safety.
Successfully saving him is damn hard and will burn through your ammo, and having a half dead guy in your back is a bit of a liability, but a few missions later he may return the favour, but if you take his high priced stuff and leave him to die, you could be wishing you had some backup further down the line when your faced with a charge of freakish monkey dog animals.
You may find a group of your teammates about to execute an enemy prisoner.
You can do nothing, or do it yourself, or you could convince them hes important and let him live, but then your teammates may question your loyalty.
Some moral decisions can have huge affects on your character.
You and a buddy could be walking down a road, all of a sudden your hit with a wave of strange poisonous gas, you have a gas mask but your ally doesnt.
He dies within seconds but you can proceed with your current mission which has its own rewards.
Or you take off your own mask and give it too him, you are knocked unconscious and wake up in a med station two days later.
Your friend brought you here and you miraculously are alive, but your mission has failed.
Hes obviously forever grateful and allies everywhere are stunned by your selfless exploit.
However you now need to regularly take a rare experimental drug to counteract the permanent effects of the mysterious gas to prolong your existance another twelve hours. The man you rescued will also give you this drug occasionally if he can find it.
So you start off as some anonymous mercenary sent to help take over the planet for your faction, and the other faction obviously wanna keep you out and take this place as there own too.
Both factions have mainly government type soldiers but the mercenaries arent as constrained by the means of which they achieve their objectives.
So you can be there just to do your job and get your money and go home, you can be a fanatic dedicated to your factions cause, or try to help the enemy when you can but have the disadvantage of being on the wrong side.
Saying or doing things which support your faction tips your characters scales to your starting faction, being very true to your starting faction will give you side missions and items you wouldnt otherwise get, your factions men will think of you as a hero and may even give you free ammo and items and offer to take you to certain areas and other advantages, like saving your ass when in trouble.
Some of your mates may get better gear or things they wouldnt otherwise have access to had you not helped them, a rookie you saw in the first level may now be a badass veteran with an invisiblity suit a week later.
But now the enemy faction sees you as more of a threat and will actively hunt you down and sent their veterans to kill you.
If the pendulum heavily swings toward the enemy faction they wont see you as much of a threat anymore, sometimes the more sane ones may even be neutral and will pretend to look the other way when they let you walk through one of their checkpoints.
They may also have better stuff, for example if you secretly sell documents on a new high tech weapon your faction was making some of their factions finest may start to use it.
But your still on the other side and they will usually try to kill you.
Your team will now be neutral, they wont attack you or be very helpful but you can forget about that tasty cake you were promised.
Killing an enemy when there is no alternative will not tip the scales to your faction, but if you do when it could be avoided, say on a stealth mission where killing isnt necessary it will affect it slightly.
Completing a side mission in a way that helps one of the factions will make your character lean towards it.
For example if you kill the guards to a building your faction is going to raid they will storm in and kill everyone and you get to loot everything and your faction loves you a little more.
Or you could lie and say that the guards are dead when they arent, the attack commences but the attack force is slaughtered.
Instead of a big base to salvage you get to take your dead friends stuff.
When your faction realises that you could have had something to do with the deaths of a bunch of their guys its not likely your boss will want to have a pleasant chat with you.
Along with this there is a reputation sort of system.
Helping out people and being excellent to eveyone makes people see you as an ok dude, being the good guy and also helping the enemy faction can still keep your starting faction friendly, but be a meanie and people will be more wary of you and your faction could be pretty freaked out if your also simpathize with the enemy a bit, for example some traders may even lower their prices as soon as they see you and you get access to other side missions.
Depending on which faction youve been good to and if you go all devil incarnate or mother theresa on everything will affect the games ending and everything in the game.
Although its usually never too late to change, if your a bad guy you can do some remarkable heroic thing which makes everyone rethink you, or you can continue being not so nice.
Same also applies to factions, but takes a bit more convincing.
The game has areas called safe zones which act as a starting point and pit stop for each area you visit.
Depending on the area of these places and your actions, they can range from a small checkpoint guarded by half a dozen guys to a big fortress protected by a platoon of elite soldiers.
The safe zones act as a kinda hub world, you can repair you weapons and armour, accept side missions and talk to the majority of people there, you can also sleep and buy new stuff.
Some of them can be attacked by the enemy faction, others cannot, some will only be attacked if youve been particularly bad to the enemy, but that will make your friendly soldiers defend you to their dying breath.
Some can be captured by the enemy faction or utterly destroyed.
Outside of these areas are the unsafe zones, these are always contested by your faction and either the enemy faction or some other hostile presence.
It could just be full of your dudes battling man-bear-pig creatures or the biggest and baddest of the bad guys.
As the name says these areas always have something trying to kill you in them, some have no friendly presence at all unless you bring a chum or few along with you, some are huge warzones full of world war I style trenches and barbed wire.
The unsafe zones are where the games side missions are completed and some accepted or started.
Many random things also happen here, your faction might start off holding a line against the enemy.
Two days later the lines collapsed and its down to a few of your guys to hold off the swarm of crazed fanatics attempting to destroy your once safe zone.
Or twelve days later the lines still holding and the gap of no mans land is a mess full of bodys and burnt out tanks.
Many of these things can be influenced or changed by your actions, some can not, but theres always something new everytime you go back to one of the unsafe zones.
Primary missions are more linear and happen in areas you cant go back to, finishing a primary mission lets you go to the next area with a safe and unsafe zone.
The primaries are usually accessed by the areas unsafe zone, but sometimes you can go right there from the safe area.
Primary missions can have a few little side quests if you explore throughly enough with multiple outcomes.
Finishing the mission itself will often present you with a choice.
Do you upload the information on the enemy troop movements to your faction or do you edit it and give your command misleading intelligence?
Gameplay wise you die in a few hits, minor injuries can be treated with stuff like simple bandages or automatic healing dispeners on more expensive suits and armours, heavier injuries need to be treated with a medical kit, but you can only carry a few.
You can also go to a medic if there is one nearby, if there isnt you bleed out and die.
Armour and weapons can be upgraded and degrade over time, through use, through mistreatment, through the environment of the world and weather conditions (plastic guns can melt in extreme heat, metal guns can more easily freeze in artic conditions), or if theres a crazy animal clawing at your vest and ripping apart your gun, you better beat its head in before that new sniper rifle of yours gets chewed in half.
Armour and weapons can be repaired by engineers or technicians found in safe zones but the job is never perfect and will charge some ammo unless your particularly in good with your faction or that particular techie.
Because your gear can never again be in tip top fresh from the factory condition you will have to scavenge around a bit and wont end up using the same stuff you got from square one to the final level.
Upgrades for guns can include simple stuff like bayonets or mini scopes for assault rifles, reworking a high powered single shot shotgun to fire grenade launcher rounds, to giving a rocket launcher three barrels.
Armour and suits can, depending on the suit be upgraded with stuff like extra armour or more ammo pouches, auto healing or stuff that can repel chemical burns (you know in Alien vs Predator the aliens head doesnt get acid melting death?)
However you cannot have all upgrades at one time, getting one will cancel out getting another, most upgrades are permanent but some gun upgrades can be removed, like silencers or bayonets.
The game will at one minute have you simpathize with the enemy faction right before another crazy fanatic tries to detonate a grenade by your head.
You will see weird happenings that not just defie, but rip apart the known laws of physics, put them in a blender and burn the remains (say if you are in an artic area and that flamethrower of yours gets ripped out of your hands into a weird gravity distortion, then it gets spat out and is half frozen but works better than it used to and now somehow the napalm has been converted to liquid nitrogen).
You will face decisions that have you thinking, should I or shouldnt I for over an hour.
You will face such horribile horrors you will run on back home to mommy and have to be reeducated on how to properly use the toilet.
And of course being the perfect game it has black humour and Monty Python jokes.
(and shurikens and lightning)