[Sticky] Xbox Links & Resources (Xbox 360, Xbox One)
Check out the general research forum for more useful links and resources that are cross-platform. The following will help you dig up information on Xbox titles only:
As of this writing in May of 2018, Xbox 360 games are the easiest delistings to research. So far Microsoft has done an admirable job of keeping their Xbox Live Marketplace pages online and not blocking Archive.org crawlers. There are plenty of 404 pages where games used to be but for the most part you can find pretty good delisting windows by sticking the URLs into the WayBack Machine.
Here are links to the majority of the Xbox.com pages organized roughly by region. Browsers (especially Chrome) will sometimes default you to your local region. You can tell by looking at the URL to see if it changed from "/en-GB/" to "/en-US/" for example. Try using Incognito or Privacy modes in your browser or a tracking-free browser.
North & South Americas
I’m terrified that this page is going to be changed soon, but for the time being I use this URL to see the whole Xbox 360 marketplace listed by release date (newest to oldest). It’s useful for grabbing the Trial Game of anything that happens to pop up so you can re-download it if it’s ever delisted.
It’s a bit tedious but you can also easily spot delistings by looking at the row of icons next to each cover. If you see that a game has a half-filled controller icon but not a full green controller icon, chances are it’s been delisted. Grab the game page’s URL, head to the WayBack Machine, and start digging! Don’t forget to queue up the Trial Game too in case it ever disappears too.
Larry “Major Nelson” Hryb is the public-facing frontman of the Xbox community. His site is home to a huge history of game release announcements, sales, and direct links to game pages that might be delisted. If I’m looking for more detail on an Xbox 360 release I always check to see what Major Nelson’s site has.