I know the standards I use to judge when a game is worth it's cost in time and money (I focus more on money because I'm a broke grad student), but I wanted to get opinions from the rest of the community on this one.  I enjoy writing reviews, but I've been stumped by finding a respectable measure of "worth playing".

I've been trying to figure this one out, and the standard I've used was $5/hr.  If a game entertains me for a day (2-3 hours), but was only $5 or less, then it was alright.  That's still favorably comparable to a movie.  What are the standards that the rest of you guys use?  Do you even consider the cost of a game when you're looking at it?  It's usually pretty clear to me that it's not worth $50 or more for me to buy a game that I play for an hour and then hate, but I'm trying to figure out where to draw the line on cost.

The other big issue I run into is "the value of playing time".  I know a game like WoW (or any other MMO) can have hours upon hours of content,  but much of it requires a tedious grind to get to.  Grinding is fun for about the first 1,000 hours you do it, across every game, your entire life.  I don't count any time spent grinding that I didn't enjoy as valuable gameplay (so if I have to grind for 10 hours before I really get to play, then those hours don't count as real content when I'm judging the game).  How do other people measure the useful hours in a game ("useful hours in a game" is such an oxymoron).

" I don't tend to think about the money side, If I had fun out of it its worth playing. "

I guess I don't have that issue a lot because I tend to keep my gaming on the PC. With steam and other stores having really cheap pc games, I tend to buy a lot and play a little of each. I would have to say that I agree with the above posts. If I enjoyed my time playing the game i consider that worth playing.. If i didn't like it I would say its not.  Regardless of how many hours I have spent on them, I base my review on how my experience in total has been. 

If it's fun, it was worth it. 
If it's engaging, it's worth it. 
If it's intriguing- eh it's iffy sometimes it's worth it sometimes it's not (sorry guys but shocker, i felt this way about Braid and Limbo- iffy not sure if it was worth it altho to be fair I bought braid super cheap recently so i guess that doesn't count =P)
 
Really, it just comes down to if I at some point stop playing because I'm bored then no matter how long or short it is it was not worth spending money on because I cannot bring myself to play it. 
See Final Fantasy XIII for examples.

I just can't see how anyone can get any enjoyment out of games if you try to verify it by a money/time variable. You' can't measure fun, either the game was good or it wasn't.

Did I like the game: Worth it

I think if you enjoyed most of the game and after finishing it you wanted some more of it then it was worth playing for sure!

" Did I like the game: Worth it "

If I'm still thinking about it long after I finished it, it was probably worth it.

i know a game is worth it when i think that it's going to be a great game. i watch or listen to reviews, watch gameplay videos. i think if it's good or not. i don't look at it money wise because most of the games cost $60. there are a few games that are cheap when they come out but still.

" I don't tend to think about the money side, If I had fun out of it its worth playing. "

The entertainment-per-hour factor doesn't work when you rent 90% of your games.  
 
A game is worth playing as long as I enjoy it.

It's not some complex equation. If I enjoyed the game then it was worth it. Otherwise no, it's not. Would you rather play great eight hour game or a bad fourty hour one?

Certainly, dollar/time ratio is important to me, but I spent $6 and 20+ hours on Arcanum and that game was not worth playing. So basically: "Do I think the game is good or not?" is the criteria for if a game is worth playing

I buy pretty much all of my games on sale so very rarely do I feel that the game was not worth the price I paid for it, even if I don't end up playing it a whole lot.

If I have to make any calculations or measurements, it was not worth playing. If it was really worth playing, I'll know.

Pretty much what everyone else says. If you enjoyed it, then it was worth it. 

If I put down the game with a feeling of satisfaction, it was worth playing.
 
If I don't, it probably means I wasted my time.

Re-playability doesn't really factor in to my decision making. It's more whether or not I enjoyed the game throughout.