It might be that only certain games are backwards compatible with the Xbox 360, and so some sites are trying to make a list of games that should be backwards compatible.
From 1up.com:
At E3 this year, Microsoft’s Xbox chief Robbie Bach dropped a next-gen bombshell on their competition by announcing that the Xbox 360 will be backwards compatible with the best selling Xbox games. Suddenly, the Xbox 360 was capable of duking it out, bullet point for bullet point, with Sony’s PlayStation 3 and its promise of playing the PS2 library. But wait… did Robbie say “best selling games?” What, so not every Xbox game will be playable on 360? Who decides what the best-selling games are, anyways?
Well, when it comes to determining backwards compatibility, the ball is entirely in Microsoft’s court. As you’d expect, they’ve already baked-in all the no-brainer Xbox games that will work on 360 (e.g., Halo 1 and 2, Knights of the Old Republic, Fable, etc.), but with the Xbox 360 launch just around the corner this November, the boys from Redmond are unofficially reaching out to the gaming community to learn what remaining games Xbox fans would like to see backwards compatible on Xbox 360. So we’re gonna help them out and ask our 1UP users, as well as the gaming community at large, as to which of the following Xbox games they’d want to see on 360 — day one, out of the box.
We present below (split into two digestible lists) 80 worthy Xbox titles Microsoft isn’t sure about. 80 games that will, over the course of the next 5 days, battle it out to the death. While there are no guarantees that the top 10 or 20 games will make it into the backwards compatibility list, or even what the cut-off number will be for the top titles, the stakes here are unquestionably high. To be sure, Microsoft will be checking out these results to gauge consumer interest in many of these excellent games. And they will act accordingly. So know that your vote will make a difference.
Visit 1Up to tell Microsoft which games must play on Xbox 360