I typically despise criticism that offers no alternative solution(s). I grew up in an environment where I had to learn to laugh and blow my nose several times lest I be "bashed" for not getting it right. The problem wasn't so much the bashing, although that wasn't fun, it was not knowing what was actually correct. It generally took several bashings before I stumbled upon a suitable solution. So rather than just say "this didn't work", "this isn't right", "I don't like", I want to offer some idea of what it is I would like. Just in case.
One thing that consistently pleases me about a video game is whether the game allows for a variety of play styles. Will my third person shooter allow for first person and vice versa. Can I use either stealth, diplomacy or feats of acrobatic skill to solve a given problem, without having to use all three? I want a game that gives me the freedom to explore and choose a playstyle that I most enjoy, or better yet, several equally enjoyable playstyles that I can access on a whim.
The Elder Scrolls IV: Oblivion probably represents one of the best realisations of this that I've encountered in my travels. There's a lot that I don't like about the game, but it's one that I can enjoy and keep playing because it's flexible and has oodles of play styles. I can play it as a first person shooter, a stealth action title, I can play it as a puzzle game, I can play it as a typical RPG, or I can generate a ruleset that requires quite lateral, or quite ludicrous paradigm shifts.
I'll admit that optimised play in Oblivion has the "All roads lead to Rome" playstyle in that you need to have everything to create an optimised character, more or less. However, it's when one starts setting rules for oneself, and ignoring optimisation that one can truly explore the variety of games on offer here. For example, stealth only kills, a naturist (nudist) class that is forbidden to wear clothing or armour, a zero kill rule - that is, complete the game without a single kill (and as many of the sidequests as possible). Try playing the game with the Atronach starsign and compare the experience to any other starsign, or try playing a Mage class character as either an Atronach or as any other starsign. While the plot of the story doesn't change, the way in which one can engage with it can change considerably.
I also found Metal Gear Solid 4 to be very flexible. It was a stealth action game, a third person shooter, and a first person shooter. Within this there were several subdivisions on offer. Should I use the new metal gear, the knife, CQC, the tranquilizer guns (pistol and rifle), and / or the various disabling traps to be the focus of my stealth gameplay. Each approach changed the game slightly and by devoting oneself to a particular style of play (knife only for instance) the way to engage with the game changed. While knife only doesn't really seem feasible for boss battles it's certainly reasonable for the rest of the game. I suspect a traps only approach would work as well, but would be considerably harder because of their very limited numbers.
Mass Effect offers this kind of game, but fails to deliver. RPGs are most likely to provide varied play, because by their very nature they offer a wide array of skills, powers, effects and possibly gameplay experiences. The problem with Mass Effect was that it used the same basic mechanical method for all in-game effects. Shooting a gun, using a biotic power, throwing a tech grenade, and throwing a normal grenade all used the same basic approach (press and hold one button, and then press another). Ironically, the character that I typically find to offer the least variety in an RPG - the fighter - was the most diverse in feel when playing the game. Shotguns, Assault Rifles and Sniper rifles were sufficiently diverse to create the illusion of some variety when compared to the other classes. The Adept and the Engineer classes were too similar, within the class and to each other. Their powers were utilised in precisely the same way (sequence of button presses), and manifested as a blue or orange glow on the enemy. This is not to say that I hated Mass Effect, or that I think it's a bad game, just that if it were to come down to choosing between the next Mass Effect, the next Metal Gear or the next Oblivion then Mass Effect would lose out.
One game that apparently has this attribute, but really doesn't is GTA IV. So many industry professionals said in their reviews that this game could be played anyway you like. The variety in gameplay is immense, infinite, and so forth. And it was these sorts of statements that tempted me across the line. Each mission follows a very specific and linear structure that requires a specific set of responses from me, and is quite unforgiving if I don't adhere to the game's expectations of me. Sure you can choose to play through the missions in differing orders, but you must play through them all to reach the end of the story regardless. Because of this the mission structure is illusionist handwaving, an attempt to deceive me into thinking I have freedom when really I don't. Outside of the mission structure I can do anything I want, as long as it's one of three things, driving, shooting or playing mini-games. I can't really re-interpret the game, the game world, or the avatar I've been given through play. I can't convince the baddies that I'm badder or better, I can't play the game through the first person perspective, I can't use stealth to solve a problem, I can't impose a set of rules upon myself that fundamentally changes the way in which to game is played. I can impose a set of rules upon myself that fundamentally changes the way in which I interpret what is represented by the game, but this doesn't change what I'm actually doing in the game, how I actually play, it just changes my perception of it. Problem is, I couldn't make it work, I couldn't make a re-interpretation of the game world strong enough to overcome the limitations imposed on me.
What's your Holy Grail of gaming? Is it graphics, story, gameplay, or is it something else? And if you don't mind sharing, what is it about this Holy Grail of yours that makes it so important?