Many times there are games you like to play, but there isn't much purpose in you owning them. For me, the most common cause of this is that I would only play with a certain group of people, so there's no reason to have multiple copies of the same game around. Many times, these games are expensive and/or hard to store. Most of the games on this list are games I haven't played, and I've talked myself out of buying for one or more reasons.
Honorable mention to Settlers of Catan 3D. The reason it didn't make the list is because it isn't really its own game. The game looks amazing, but there's no way I could ever justify the cost.
#7 Memoir '44
I used to own Memoir '44, but I traded it away. I grew tired of the game system, and felt that it was lacking an epic feel. I've heard that playing with 8 players in the Overlord format helps that notion, but I don't have 8 people to play Memoir with, so that would be wasted money and space for me.
#6 Wings of War
Let me be specific here. Wings of War with the plane miniatures, and all the stuff that makes it look really cool. I've played Wings of War, and I have a good time playing it. It's fun to get everything set-up and turn the table into a war zone. My gaming dad's brother owns a lot of the game, and he visits once, sometimes twice, a year. We'll get together a big group and play then, but outside of that, it's something we wouldn't play.
I've never played Heroscape, but man does it look awesome. The miniatures look amazing, and the terrain looks even better. The rules seem complex enough to be interesting, but not overly complicated. The problem I run into is storage space, and money. I'd love to play with someone who has the game, but it's not something I'm willing to get for myself.
#4 Descent 2.0
I owned Descent for about a year, and over that time, I never got it to the table. The game is big, bulky, and has a lot going on. Descent 2.0 does seem to fix a lot of that, but it has a potential issue, Campaign play. Now, I love the idea of a Campaign, but right now, my gaming time is sporadic, and I feel like this would sit on the shelf and gather dust while shorter games come out. Plus it's something that seems hard to bounce in and out of, so that restricts play to having the same set of people.
Crokinole is on this list for the simple reasons of cost and storage space. Yes, I know that the boards can be hung on a wall, and that removes a fair amount of the issue of storage, but it increases the cost. See, if you're going to put something on the wall, it should look good. That means buying a more expensive board. Plus, without ever having played the game, it's something I don't want to invest in right now. Maybe someday, but not soon.
Flicking a disk around a track just sounds like a good time. The problem with that, once again, is storage. The track for Pitchcar is rather overbearing. It would be a lot of fun to own the game, but then I'd want to get all the cool pieces, the crosses, the loops, jumps, etc. and that just adds cost to everything. This is best left to the play if I ever get a chance, but don't buy category.
#1 Twilight Imperium 3rd Edition
This is the inspiration for the list. When I first heard of TI3, I knew I wanted to play it. The game sounds fascinating, with a lot of depth and choice. The problem, 8 hours. There is no way that I can get at least 6 people together to play a game for 8 hours. It just won't happen. Even if it did, there's no way I'm storing the game at my house the other 364 days of the year when it didn't get played.