SteamWorld Dig 2
SteamWorld Dig 2 is a metroidvania that adds RPG-style progression elements to the formula. Not only are you getting items which help you platform and fight, but you are also digging deeper into the earth and temples, giving you more money and XP to get upgrades. This is a fantastic metroidvania with a lot to explore and have fun with.
The main mechanic differentiating this from other metroidvanias is all the digging. You're constantly navigating through dirt to find gems and minerals to sell for further upgrades. This gives a very steady progression to the game, but it can also feel grindy at times. The digging does make it feel slower and more chill than other metroidvanias.
Eventually the game opens up to where you have options in three different areas where you can dig around and search for things. There's also a series of puzzle caves that provide good variety and challenge. So there ends being a lot of variety of things to do at any given time. I found that the game always had more things up its sleeve to provide interest and challenge to the player. For instance, there's high-risk high-reward equipment that make the game more punishing.
The aesthetics are this goofy, Flash-animation-looking style sprites. All the SteamWorld games have this kind of look, with a variety of colorful "steambots" instead of humans. There are humans too, but they are caveman NPCs if not enemies. It's a lot of fun.
The game sequence halfway through with the evil Vectron is legitimately scary and unsettling. They do a good job making the Vectron feel different than the Steambots as well as make them good villains.
I love all the SteamWorld games (which are all different genres) and SteamWorld Dig 2 is no exception. I highly recommend it to people who like metroidvanias, though it is slower paced than most. The RPG elements are fun and work very well.
I generally don't recommend its predecessor Steamworld Dig 1. It's just not as polished or interesting. It's perfectly serviceable, but Steamworld Dig 2 is just a far more complete game.