When I think of flash games, I have a few in mind like Machinarium that due to their dependence on Flash will most likely die with it.
Gnash gave us reason to hope but when large companies gave up on Flash, so did GNU. Then Lightspark looked to be the great hope but 12 years on now and it still can't play most basic games.
Last year, members of Newgrounds spoke of creating a flash player for games and I honestly didn't expect anything to come of it because many have tried and gotten nowhere but, their progress is going surprisingly fast.
Check it out. They plan on full support of flash games by next year. We shall see.
http://ruffle.rs/
https://github.com/ruffle-rs/ruffle/wiki/Roadmap