Whiteblade999: PC:
Assassin's Creed 2
Assassins' Creed: Brotherhood
Assassin's Creed: Revalations
Darksiders II
Shadowrun Returns
Sleeping Dogs
Ys 3
Not in, but I'll tell you how I would tackle that backlog personally (including only the (PC) games I'm familiar with)
First of all, the AC series should be played in order (naturally).
That is, AC2, then AC:B, finally AC:R. You might wanna play through one of them every two games - three, even two AC games in succession might be a bit much.
Shadowrun Returns: I would personally wait until they release the Berlin DLC, but that's just me. If you have no plans to get that, then this could be a good candidate to start with.
Sleeping Dogs is a great open world game and one that will keep you entertained for hours. I think I clocked nearly 20 hours onto it.
I haven't played any of the Darksiders games, but I think they're pretty well received. Up to you really when you wanna play it.
Well...that's all I know of the games you mentioned. That would make my list look something like this:
AC2 -> Sleeping Dogs -> AC:B -> Darksiders II -> AC:R -> Shadowrun Returns.
But, another way to tackle that backlog is to check howlongtobeat.com, find out which games are the shortest on that list, and start with them. The shorter your backlog, the easier it is to keep track of the games you still need to play. Keep in mind though, that certain games have a story that's continued from game to game (such as the AC series). If there's a year between installment playthroughs, it can be more difficult to get back to the story if you've forgotten everything that's happened so far.
Sorry I can't be any more helpful!