My dream game would be something of a supergame, a behemoth of an MMO with open-endedness at its core. Such a game would allow for gaming of all kinds to take place within the same universe, thus bringing anyone and everyone together, to engage and interact with one another.
Let's start with combat. Combat will be FPS-based, where players use their mouse skills to defeat opponents. That's not to say someone else can't utilize other techniques at their disposal to benefit themselves on that front (more below). Larger battles can see more co-op between players, as strategy starts taking an advantage over mindless brute-force fragging. Examples might include utilizing combatants of various disciplines and abilities on specific tactical fronts. Even larger warfare can see sides utilizing unconventional tactics to win, through sabotage, espionage, bribery, and so forth.
Allowing for all this to be possible would be crafters/engineers. Rather than let developers create everything for us, it would be the duty of players themselves to design and create items such as weapons, armor, and other elements for such battles. Designs and blueprints can be created by engineers, whilst player-owned factories and fabrications create prototypes or full-scale manufactures of said items. Items themselves can be anything, from the screws of ones power-boots, to the microprocessors of ones helmets. Indeed, a high-grade engineer could even conceivably design something enabling warriors to auto-aim via mechanical devices, if the price is right. Of course such a feat would only be possible via actual in-game programming which factors all attributes of said warrior, among other things. This is not to say the above are examples of meta-gaming, developers will have to pre-design said systems but also allow for a great degree of flexibility. An example might be something of a telescopic device on a melee weapon like a sword. Practically worthless, but still possible. Another example might be robotic legs attached to a ranged weapon. Worthwhile with some in-game programming. The prototype can then either be a motion-detecting sentry, or a fully automated AI droid, all depending on the skills of the engineer/programmer.
Supporting all these characters would be resource harvesters. Resource harvesting would encompass a large part of such a game, as anything and everything could be a resource. Minerals and metals can be mined out of the ground or from asteroids, either by hand, via robotics, or via automated harvester vehicles (all designed by players of course). Gasses can be collected on planets, asteroids, interstellar-space, or even stars (should some be crazy enough to attempt it). Organic entities could also be regarded as a resource, assuming the right research is conducted by other professions. Plant-like lifeforms could be useful as the sap emanated from their bark might prove to be an excellent lubricant for machinery, or perhaps certain compounds within its structure could be useful for drugs, medicinal/hallucinatory or otherwise. Even junk could be regarded as a resource. Players could, without any skills whatsoever, utilize any and all means of acquiring junk. From the use of ones hand and shovels, to vehicles traversing the surface (and subsurface) of planets, to spaceships floating within vast stretches of floating debris of some long-forgotten space war.
Next, both of the above professions would rely on another type of player, the architect. Much like engineers, architects will have the ability to design and engineer structures, from factories to forts, to homes and even space-structures. The profession will indeed be engaged in a back-and-forth cooperation between resource harvesters, engineers, and factory owners, among others. Some could be in a role of consultant (meta-gamed of course). Perhaps engineers could point out the need for automated sentry-weaponry in the blueprint of a fortification structure, or perhaps resource harvesters could request the architect to allow for modular armor sockets for their resource-holding structures. Speaking of homes, for those with an adequately-sized monetary account, one could perhaps hire an architect full-time to work on their dream home. Will the home have structural armor? Perhaps sentry-guns, or small compartments scattered around to house auto-bots? Or maybe underground cavities to keep a personal and respectable droid battalion? Modular structures could house a mini green-house garden (drug-field?), or perhaps expensive sports/luxury vehicles to show off to guests?
Constructing structures of course brings up other related professions, such as various town/city professions like Doctors/other medical specialists, vendors, shopkeepers, crafters, tinkerers, wares-specialists, refugees, politicians and bureaucrats, underbelly miscreants like bounty-hunters, gangsters, thieves, smugglers, and of course enforcers like private/public security, police, and the military, thus bringing us full-circle.
Such a game would give almost everyone the chance to play with each other, something most other MMOs lack. The open-ended nature of such a game would ensure unbelievable depth for players and provide years of fun, either through exploration of the universe, or via their professions, or via their interactions with players, or via experimentation in said profession, or via meta-gaming. I tire of seeing game after game massage the same trite message of their games being fun. Indeed they are fun, but for just that particular segment of the gaming population. What I want more than anything is interaction between players of different gaming mindsets. I want to see the look on the face of a Warrior chief when he discovers that his best man owns a house with a pretty flower garden. I want to see a crazed engineer design the most outlandish junk that they actually become collectors items for wealthy players. I want to see a role-playing village idiot annoy everyone I want to see a home of a senior politician turn back on the owner, as the blueprint contained hidden programming from an assassin saboteur. I want to see cooperation between townsfolk such that even non-combat inclined professionals do whatever it takes to defend (or survive, even if it means escaping like a coward) against an onslaught of bloodthirsty vermins.
Ultima Online (from 97-99) popularized the entire MMO genre, and started the ball rolling on open-ended gaming. SWG (preCU) was to be its great successor, promising almost everything stated, and it was very much on the way to being that (until the CU). And what do we have now?
Nothing. Nothing at all.
We have WoW, which is a level-lewt-combat fest. We have TOR coming up, which has nothing open-ended about it, almost completely combat-based. We have STO, which is primarily combat with some sprinkling of crafting in it, but almost completely mission/quest-based. We have various anime-based MMOs which typically puts little effort into consistency, often over-exaggerating elements, resulting in games that makes little sense. That's it. Blizzard/Fallout people/Rockstar may have something up their sleeves, but who knows where they'll take their games.
In my opinion, MMO gamers are currently living the dark ages. They are wasting time playing these games that will be all but forgotten in a few years. And that is because there will be yet another indistinguishable MMO from all the rest, which yet again focuses on levelling/loot acquisition/combat against players and monsters. Where actual role-playing (ala MMO'RPG') comes in is anyones guess. The genre is headed no-where with all these clones about, and until someone has the balls to create something truly magnificent, an open-ended game, that's exactly where it'll stay.