Windows Phone Central reports that there are more and more old Xbox Windows Phone titles showing up with Windows Phone 8.1 support. These titles include old favourites from the time of Windows Phone 7, a time when HTC was the leader in the Windows Phone space. Some of the old favourites include, ilomilo, Parachute Panic and Crimson Dragon: Side Story. Do note that these games have not appeared all of sudden but have been resurrected from the dead over a period 3 months or so.
As for the complete list of Windows Phone titles that have gradually shown up online, you can click here.
It was just a few months ago that Microsoft pushed out its quarterly report that showed that low RAM devices indeed rule the Windows Phone Store. The report was clearly aimed at developers but it did reveal a lot that was happening in the Windows Phone space along with consumer preferences which are indeed vital for devs.
Seems like the migration has begun and the games have started to pour in with more support for Windows Phone 8 and lower RAM requirements for games and apps. Still then, Microsoft indeed has a long way to go when it comes to closing the app gap with other ecosystems.