The Metroidvanias Steam Summer Sale

Rabi-Ribi was a surprise in just how amazing that game was. I'm not a fan of that sort of art style, but the gameplay is fantastic and the story is fine too. Definitely recommended.

Everyone has already praised Ori to the moon, but I liked it enough to buy the two separate versions. Something I would never do for most other games. Grab the definitive edition and never look back.

Dust is a great one too. Fun combat and it gets chaotic with the right powerups. Story and voice work is fine here too, but it's slow. Recommended.

Hey Enkeria,

Of the metroidvanias I got, one strangely weren't cited yet.
Dust: An Elysian Tail, Guacamelee! Super Turbo Championship Edition (I've got the Gold one as well) and Shantae and the Pirate's Curse but also Risky's Revenge. I love them to bits.

Dust is fast-paced and requires a little puzzle-solving. There is a bit of crafting in there, it has a leveling system. You can reach combos rather fast... It can be light-hearted and sad at times.
Guacamelee relies a LOT on abilities you learn during your quest... There are techniques like a flaming shoryuken, a vertical dropkick, a headbutt... all wrestling-themed. You'll even have to switch forms and worlds to progress further.
Shantae is quite more relaxed and no less fun.

I could say much more about them.

I also acquired Axiom Verge, Aquaria, Cally's Caves 3, the Shadow Complex, Owlboy but I haven't tried them yet.
I tried the demo version of Valdis Story as well and backed for Indivisible.

Hollow Knight is totally recommended. Outside of IGAvanias, it's probably the best game of that style that I have ever played (I played A LOT), and I think I'm only halfway through. Other than the breathtaking art direction and animations, and the gorgeous OST, it has a lot of character and has complex Metroid style maps, absolutely not linear and can make you wander for a bit but you don't get lost pointlessly and frustratingly. The exploration is very rewarding, and I think that this game is one of the few that truly embrace the Metroid philosophy. Axiom Verge did this approach in a horrible way IMO. "Yay, new skill! You can use it in fifty bazillion places you've already been in, but 99% of them lead to pointless collectibles and weapons you'll use just once for the sake of novelty! Let's make the player wander for hours, because Metroid is about getting lost!" yeah, no.

Before, this spot was Dust's which has fantastic graphics and music, a fun and rich combat system, awesome story. The only downside is that it was way too easy on the normal setting for me. I had to play the highest difficulty right away or I would've felt omnipotent almost the entire time.

Guacamelee is hard, and some platforming sections required to get some secrets are absolute HELL (like Super Meat Boy level), but it was so fun and rewarding! Also with a lot of personality and a deep combat system once you got all the skills.

Valdis Story is also cool. It has a somewhat in-depth combat system, with a lot of skills, skill trees, stats you can invest in and so on, many characters to play as. Strangely though (I usually complete these games 100%, with all the achievements and stuff) it didn't keep my attention for more than one playthrough. I didn't replay it on higher difficulties, or with other characters, nothing (also, achievements were far too many and time consuming, other than difficult). I believe it's because the environments and art style were a bit too generic, and the maps were nothing too special. It's a really fun game, and I enjoyed my playthrough with it, but for a game that's supposed to be greatly replayable it didn't quite click with me.

I have yet to buy Ori, Owlboy, Rabi Ribi and Shantae Half Genie Hero; they look really promising but I have too many games to play atm, there's not really a point in spending more money now.