My own (highly subjective!) opinion on "value for money" for a game is largely based upon "did I have fun?". Unfortunately, I don't often feel like "I had fun" playing many of the more recent games (like say games in the last five years or so, with a few exceptions). Games that I do have fun with, I often think, "It's too bad it wasn't good enough to play more than once".
I often buy my games for their full retail price (or even more!), and often end up disappointed. That's not to say it's entirely the fault of the game developers. It's just that I've been gaming so long that I look for more interesting, unique, and fun experiences. I'm not looking for "the next call of duty" game. I'm not looking for "the next final fantasy". I'm looking for experiences that are either unique, or new takes on old formats. Back in the day, a "new take on an old format" was including a really well conceived and fun story for a shooter (Halo!). It's not the norm anymore since games like Battlefield and Call of Duty are conquering that market. Back in the day, a job system and upgradable skills were really interesting and allowed a lot of customization of characters for interesting battle (or unique gameplay).
So, let me be a bit weird and clear here. I'm going to define how I judge "value" of a game.
1. I find the game to be fun a majority of the time. This means I finish the game and was enjoying the entire time I was going to the end. I have a lot of games I never finish because I get burned out on the game. The combat burns me out, the skill progression system wasn't planned for a full playthrough (meaning it was too short to be worthwhile and I maxed it out before even completing the first 3 missions or levels because it was too easy to do so or was too beneficial not to... which tends to translate to about 12 hours of actual progression in game before you max out a skill tree or a progression system), or the game stops throwing new and interesting challenges at me (also known as... the game let me get too powerful too early on and they hadn't planned on players ever finishing the game or vast chunks of the game as overpowered as I got). Or, sometimes the story just drags on forever and goes nowhere... predictably. In short, if I finish the game, it's usually worth the investment of $60.
2. Upon finishing a game, I either immediately want to play it again, or put plans in the back of my head to tackle said game again, but trying different things (be these self-imposed challenges, roleplaying, exploring mechanics, making different choices, etcetera). I will pay $20 for a movie and eventually watch it again (or watch it a lot)... Why cannot games get this same sort of value? A game that I do not ever want to play again because I did everything the first time (or did everything I cared about the first time) immediately makes me think the game is worth $40 at most and $30 more likely.
3. Ability to recommend a game to a friend or a family member. If I can't say without a doubt that the game I just played should be played by everyone I know... or at least some of the people I know... Then, I don't think the game is worth the money spent. Even if I had fun with it, even if I want to play it again, if there are just things in it that only I would enjoy (which has happened), then I cannot recommend it and it loses some value in my eyes. To me, video games are a bit more valuable as "shared experiences". I could talk endlessly about Chrono Trigger and how amazing I think it is... But, if my friends never play it and there's nothing in it I can recommend them play it for... I'm essentially talking to myself. Likewise, if I recommend a game, but provide a caveat to purchasing it, that drastically lowers its value to me as well. I cannot for the life of me recommend playing a game like "The Last of Us" because the highlights of the game are the story... which you can get on YouTube for free... and you can safely ignore the fairly boring and bland combat/stealth nonsense in the rest of the game (or maybe pick up a game that does both of those much better if that's what you're looking to get out of the game). I cannot recommend a game like Battlefield Hardline because despite the fact that I enjoy it, it comes with the caveat: "It's like if Battlefield were made by the Call of Duty people. Maps just as small, game modes as boring, most gadgets as useless". I cannot recommend Other M because of the caveat "It's an amazingly fun Metroid game... but you have to ignore the entire story and the fact that a story exists to enjoy it".
That's how I often determine value of a game for myself. Granted, some of this is "after the fact" review by myself, but it isn't any less valid. I've told friends of mine, "Yeah, it's a good game, but don't pay $60 for it. Wait until a price drop to $20. It's a great game for $20." My friends trust my judgment, and I often trust theirs (they give me the same advice). That doesn't stop us from making impulse purchases based on riding the hype train... But, it keeps us from making impulse purchases on other games that we "didn't have money for purchasing the day it came out". If one of us gets it, they provide the review for the rest of us before the rest of us drop money on it.
EDIT: Ha... I forgot why I was posting in the first place. I was going to say that I don't really define "value for money" in games based upon genre. Genre is such a weird thing to base "value for money" on in a video game. Every person has their individual tastes for the kinds of games they like, but very few limit themselves to one or two genres. Most people have at least a few games from every genre of video game because they wanted to see what it was like. I've got a racing game, a fighting game, a sports game somewhere, and an RTS or two. But, my preferences lie in sandboxes, shooters, turn-based-strategy games, RPGs, and creative/simulation games. Doesn't mean I don't know a good fighting game worth my money. Doesn't mean I don't know a good racing game worth my money (call me weird, but I love Forza despite not really buying many of the games... I like that racing is less about "go fast" and more about braking, cornering, maneuvering, etcetera... I don't often own these games 'cause I just don't have the time to play them... And my OCD completionist attitude towards gaming would probably murder me in Forza since I'd want to buy every car and every part for every car). I've played some fairly fun sports games worth my $60 as well.
We each have our preferences, but luckily none of us are stuck with them as the only games we're allowed to play. Value for money is determined by fun and personal preference.