What makes a good game good is pretty subjective. Some people actually like that atrocity MW2, for example. I thought it time to clarify my criteria, since I seem to be writing an awful lot of these reviews.
First of all I don't play competitively. I never have, I never will. I've sworn an oath to myself. The day that I play competitively is the day I stop playing video games entirely. Because of this, online portions of most games will feature very little, if at all. That's also why you'll never see me review things like DOOM, UT, CSS and the like, and is why my reviews of MP-centric games like COD and Battlefield will be a bit odd. I also tend to stray away from the online portions of games like COD and BF, which is at odds with most people around here. Oh well.
Another deciding factor for me is immersiveness. I expect a game to draw me in in such a way that I don't even realise I'm in a game. I don't want that to be Gareth Gobulcoque's pipboy, I want that to feel like it's my own. I don't want that to be Freeman's hand on that revolver, but my own. Obviously, the more immersive the game is the more I'm going to like it. Typical immersion breakers, for me anyways, are game crashes, random bits of unexplainable lag, respawning baddies, bullet-sponge enemies, graphical errors, dialogue errors, things like that. Basically anything the game does that reminds me that I'm actually playing a video game.
The DRM of a given game also factors in significantly as to whether or not I like it. I have a personal policy regarding software, one that overrides the EULA whether the EULA likes it or not. Simply, it's MY machine, it's MY rules. Software should only do what the box implies, and should NEVER willingly interfere with other software. Generally, the less intrusive the DRM scheme the better. Some schemes get automatic points off. SecuROM, for example, is an automatic two point deduction in score. Something like Ubi's latest scheme is an automatic DO NOT BUY, regardless of how good the game 'protected' by it is. That DRM is the reason I've never bought, or even pirated for that matter, Assassin's Creed 2. I don't want to even support the notion that the game's good because of that DRM.
Storyline is a HUGE selling point for me. I MUST have a good storyline if I'm going to rate a game highly. This is yet another reason MP-centric games will always do poorly compared to SP-only games. I buy ALL my games for the SP, and most of the time that's the only mode I bother playing. Again, I don't generally find competitive play fun, I don't play competitively, thusly I won't have fun if I bother with the MP. And if I don't have fun I will dock a game points. And that isn't fair, because such point reductions would not be because the game itself is bad but because I simply don't like that mode of play.
I don't have a budget at all. All the games I review I personally played, and they were played on Boot to the Head over yonder. I always include a section of how well a game runs on it. All games are run at 1600x1200 unless otherwise noted, and you can assume medium settings. I run very little AA/AF because, to put it bluntly, I don't need it.
Suffice it to say that if I claim a game runs great you will have NO trouble running it, fellow OCNers.
Control intuitiveness is also on the list, though I won't always mention it. Usually if I do, that means there was problems with it. Racing games, as well as any GTA style game where lots of driving is to be done, will usually be played with my wired 360 pad. All other games are played with MKB. Basic gist of this is: Easier to map custom controls/learn default ones = better score, and again I won't even mention it if there isn't a serious issue.
If there are DLC that I've played I'll also include a note about them, but I won't mention them nor will I put a significant emphasis on them.
Replayability also factors in. I won't often mention it at all, and even when I do it's only a passing mention, but generally the more likely I am to play it again after beating it the better the score.
Lastly I assign a game a score. This score is in the x/10 format, but that X could be anything from a number, to a phrase, image macro, emote, hell even a reaction video. Depends on my thoughts on the game in question. And remember, this is my opinion on the game. It's what I think of it. If my thoughts on Game X offend you then so be it.