I made a list of indie games on GOG.com that's also available on Playstation 4. If I left anything out let me know.

https://www.gog.com/mix/gogcom_games_on_playstation_4

I'll wait for flash sales in the future. Any games on the list are any good?

There are lots of great games on the list, but whether you'd agree with that completely depends on your personal taste and preferences, and you haven't told us anything about them yet.

Metro games indie?

Without knowing your tastes, it is difficult to say. Steamworld Dig, shower, is a underrated gem.

some of them are really great

Errr...

Nice GOG Mix, would be neat to see a similar like "GOG games on Playstation 3" as well.

Apotheon is on sale for around $5 bucks until tomorrow. Recommended?

Shower sure is an underrated gem, all right.

Basically what Leroux said, and I strongly encourage you to watch YouTube footage to see what the games are like.

Added Screencheat to the list.

Updated w/ several games to the list.

BUMP.

Added: Dying Light: The Following Enhanced

Dying Light doesn't seem even remotely indie.
Is it though?

what is "indie"?