Sunset Overdrive

We'll see. MS doesn't have the brightest record with developers they work with.

It's not a flop,but deserves much more sales,for its quality,Shadow of the Colossus one of the best games of all time.

Is it considered a flop? It sold over 3m in all consoles. 

MS is mean to many developers/publishers. However, that is how they are so successful. Nice finish lasts in this world no matter what anyone tells you.

Eternal Darkness, F-Zero GX, Viewtiful Joe, Battalion Wars, and probably a bunch of other GC games that I'm currently forgetting.

I really enjoyed the Dynasty Tactics series too, though sometimes I felt it was a tad too restrictive (there were some fights were it was clear they wanted you to make a few specific moves). Trying to set it up so that you could chain 2 or 3 attacks in a row and take out Lu Bu in one go was a lot of fun though heh, very excited to hear they're making a sequel!

I suppose, if we want to go back a ways, there's plenty of quality games that got overlooked as they were released in the twilight years of a system.

On the Nintendo, for instance, the famously expensive Little Samson was a superb game that I've only played on emulators, and perhaps the most impressive achievement on the system never released in North America and is hardly known by anyone these days (Mr. Gimmick/Gimmick!). 

I'm sure most consoles have some game like this whose only crime is releasing onto a console that people had lost interest in.

Can you believe I still find some retailers that want to sell it for 40€? After all this time?

On topic, my answer is Megaman Zero collection and the ZX and ZX advent games. Some of the best platforming games ever made, and Capcom made such poor work at its distribution they barely sold any. I still want to buy those, dammit.

The Wonderful 101 deserved a whole lot more than it got.

Final Fantasy Tactics A2 and Advance Wars Days of Ruin